diff --git a/Sources/Generator/Content/DefaultValueProvider.swift b/Sources/Generator/Content/DefaultValueProvider.swift
new file mode 100644
index 0000000..d51877b
--- /dev/null
+++ b/Sources/Generator/Content/DefaultValueProvider.swift
@@ -0,0 +1,6 @@
+import Foundation
+
+protocol DefaultValueProvider {
+
+    static var defaultValue: Self { get }
+}
diff --git a/Sources/Generator/Content/Element+LocalizedMetadata.swift b/Sources/Generator/Content/Element+LocalizedMetadata.swift
index 40c0f79..2de7a18 100644
--- a/Sources/Generator/Content/Element+LocalizedMetadata.swift
+++ b/Sources/Generator/Content/Element+LocalizedMetadata.swift
@@ -57,7 +57,7 @@ extension Element {
          - Note: If this value is inherited from the parent, if it is not defined. There must be at least one
          element in the path that defines this property.
          */
-        let moreLinkText: String
+        let moreLinkText: String?
 
         /**
          The text on the back navigation link of **contained** elements.
@@ -145,77 +145,52 @@ extension Element {
 
 extension Element.LocalizedMetadata {
 
-    init?(atRoot folder: URL, data: GenericMetadata.LocalizedMetadata) {
+    init?(atRoot folder: URL, data: GenericMetadata.LocalizedMetadata, log: MetadataInfoLogger) {
         // Go through all elements and check them for completeness
         // In the end, check that all required elements are present
-        var isComplete = true
-        func markAsIncomplete() {
-            isComplete = false
-        }
+        var isValid = true
+
         let source = "root"
-        self.language = log
-            .required(data.language, name: "language", source: source)
-            .ifNil(markAsIncomplete) ?? ""
-        self.title = log
-            .required(data.title, name: "title", source: source)
-            .ifNil(markAsIncomplete) ?? ""
+        self.language = log.required(data.language, name: "language", source: source, &isValid)
+        self.title = log.required(data.title, name: "title", source: source, &isValid)
         self.subtitle = data.subtitle
         self.description = data.description
         self.linkPreviewTitle = data.linkPreviewTitle ?? data.title ?? ""
-        self.linkPreviewImage = log
-            .linkPreviewThumbnail(customFile: data.linkPreviewImage, for: language, in: folder, source: source)
+        self.linkPreviewImage = data.linkPreviewImage
         let linkPreviewDescription = data.linkPreviewDescription ?? data.description ?? data.subtitle
-        self.linkPreviewDescription = log
-            .required(linkPreviewDescription, name: "linkPreviewDescription", source: source)
-            .ifNil(markAsIncomplete) ?? ""
-        self.moreLinkText = data.moreLinkText ?? Element.LocalizedMetadata.moreLinkDefaultText
-        self.backLinkText = log
-            .required(data.backLinkText, name: "backLinkText", source: source)
-            .ifNil(markAsIncomplete) ?? ""
+        self.linkPreviewDescription = log.required(linkPreviewDescription, name: "linkPreviewDescription", source: source, &isValid)
+        self.moreLinkText = data.moreLinkText
+        self.backLinkText = log.required(data.backLinkText, name: "backLinkText", source: source, &isValid)
         self.parentBackLinkText = "" // Root has no parent
-        self.placeholderTitle = log
-            .required(data.placeholderTitle, name: "placeholderTitle", source: source)
-            .ifNil(markAsIncomplete) ?? ""
-        self.placeholderText = log
-            .required(data.placeholderText, name: "placeholderText", source: source)
-            .ifNil(markAsIncomplete) ?? ""
+        self.placeholderTitle = log.required(data.placeholderTitle, name: "placeholderTitle", source: source, &isValid)
+        self.placeholderText = log.required(data.placeholderText, name: "placeholderText", source: source, &isValid)
         self.titleSuffix = data.titleSuffix
         self.thumbnailSuffix = log.unused(data.thumbnailSuffix, "thumbnailSuffix", source: source)
         self.cornerText = log.unused(data.cornerText, "cornerText", source: source)
-        self.externalUrl = log.unexpected(data.externalUrl, name: "externalUrl", source: source)
-        self.relatedContentText = log
-            .required(data.relatedContentText, name: "relatedContentText", source: source) ?? ""
-        self.navigationTextAsNextPage = log
-            .required(data.navigationTextAsNextPage, name: "navigationTextAsNextPage", source: source) ?? ""
-        self.navigationTextAsPreviousPage = log
-            .required(data.navigationTextAsPreviousPage, name: "navigationTextAsPreviousPage", source: source) ?? ""
+        self.externalUrl = log.unused(data.externalUrl, "externalUrl", source: source)
+        self.relatedContentText = log.required(data.relatedContentText, name: "relatedContentText", source: source, &isValid)
+        self.navigationTextAsNextPage = log.required(data.navigationTextAsNextPage, name: "navigationTextAsNextPage", source: source, &isValid)
+        self.navigationTextAsPreviousPage = log.required(data.navigationTextAsPreviousPage, name: "navigationTextAsPreviousPage", source: source, &isValid)
 
-        guard isComplete else {
+        guard isValid else {
             return nil
         }
     }
 
-    init?(folder: URL, data: GenericMetadata.LocalizedMetadata, source: String, parent: Element.LocalizedMetadata) {
+    init?(folder: URL, data: GenericMetadata.LocalizedMetadata, source: String, parent: Element.LocalizedMetadata, log: MetadataInfoLogger) {
         // Go through all elements and check them for completeness
         // In the end, check that all required elements are present
-        var isComplete = true
-        func markAsIncomplete() {
-            isComplete = false
-        }
+        var isValid = true
+
         self.language = parent.language
-        self.title = log
-            .required(data.title, name: "title", source: source)
-            .ifNil(markAsIncomplete) ?? ""
+        self.title = log.required(data.title, name: "title", source: source, &isValid)
         self.subtitle = data.subtitle
         self.description = data.description
         self.linkPreviewTitle = data.linkPreviewTitle ?? data.title ?? ""
-        self.linkPreviewImage = log
-            .linkPreviewThumbnail(customFile: data.linkPreviewImage, for: language, in: folder, source: source)
+        self.linkPreviewImage = data.linkPreviewImage
         let linkPreviewDescription = data.linkPreviewDescription ?? data.description ?? data.subtitle
-        self.linkPreviewDescription = log
-            .required(linkPreviewDescription, name: "linkPreviewDescription", source: source)
-            .ifNil(markAsIncomplete) ?? ""
-        self.moreLinkText = log.moreLinkText(data.moreLinkText, parent: parent.moreLinkText, source: source)
+        self.linkPreviewDescription = log.required(linkPreviewDescription, name: "linkPreviewDescription", source: source, &isValid)
+        self.moreLinkText = log.required(data.moreLinkText ?? parent.moreLinkText, name: "moreLinkText", source: source, &isValid)
         self.backLinkText = data.backLinkText ?? data.title ?? ""
         self.parentBackLinkText = parent.backLinkText
         self.placeholderTitle = data.placeholderTitle ?? parent.placeholderTitle
@@ -228,7 +203,7 @@ extension Element.LocalizedMetadata {
         self.navigationTextAsPreviousPage = data.navigationTextAsPreviousPage ?? parent.navigationTextAsPreviousPage
         self.navigationTextAsNextPage = data.navigationTextAsNextPage ?? parent.navigationTextAsNextPage
 
-        guard isComplete else {
+        guard isValid else {
             return nil
         }
     }
diff --git a/Sources/Generator/Content/Element.swift b/Sources/Generator/Content/Element.swift
index 6b7d1fa..b6a1e28 100644
--- a/Sources/Generator/Content/Element.swift
+++ b/Sources/Generator/Content/Element.swift
@@ -157,122 +157,130 @@ struct Element {
      - Parameter folder: The root folder of the site content.
      - Note: Uses global objects.
      */
-    init?(atRoot folder: URL) {
+    init?(atRoot folder: URL, log: MetadataInfoLogger) {
         self.inputFolder = folder
         self.path = ""
 
         let source = GenericMetadata.metadataFileName
-        guard let metadata = GenericMetadata(source: source) else {
+        guard let metadata = GenericMetadata(source: source, log: log) else {
             return nil
         }
 
+        var isValid = true
+
         self.id = metadata.customId ?? Element.defaultRootId
-        self.author = log.required(metadata.author, name: "author", source: source) ?? "author"
-        self.topBarTitle = log
-            .required(metadata.topBarTitle, name: "topBarTitle", source: source) ?? "My Website"
-        self.date = log.unused(metadata.date, "date", source: source)
-        self.endDate = log.unused(metadata.endDate, "endDate", source: source)
-        self.state = log.state(metadata.state, source: source)
+        self.author = log.required(metadata.author, name: "author", source: source, &isValid)
+        self.topBarTitle = log.required(metadata.topBarTitle, name: "topBarTitle", source: source, &isValid)
+        self.date = log.castUnused(metadata.date, "date", source: source)
+        self.endDate = log.castUnused(metadata.endDate, "endDate", source: source)
+        self.state = log.cast(metadata.state, "state", source: source)
         self.sortIndex = log.unused(metadata.sortIndex, "sortIndex", source: source)
         self.externalFiles = metadata.externalFiles ?? []
         self.requiredFiles = metadata.requiredFiles ?? [] // Paths are already relative to root
         self.images = metadata.images?.compactMap { ManualImage(input: $0, path: "") } ?? []
         self.thumbnailPath = metadata.thumbnailPath ?? Element.defaultThumbnailName
-        self.thumbnailStyle = log.unused(metadata.thumbnailStyle, "thumbnailStyle", source: source) ?? .large
-        self.useManualSorting = log.unused(metadata.useManualSorting, "useManualSorting", source: source) ?? true
+        self.thumbnailStyle = log.castUnused(metadata.thumbnailStyle, "thumbnailStyle", source: source)
+        self.useManualSorting = log.unused(metadata.useManualSorting, "useManualSorting", source: source)
         self.overviewItemCount = metadata.overviewItemCount ?? Element.overviewItemCountDefault
-        self.headerType = log.headerType(metadata.headerType, source: source)
-        self.languages = log.required(metadata.languages, name: "languages", source: source)?
+        self.headerType = log.cast(metadata.headerType, "headerType", source: source)
+        self.showMostRecentSection = metadata.showMostRecentSection ?? false
+        self.languages = log.required(metadata.languages, name: "languages", source: source, &isValid)
             .compactMap { language in
-                    .init(atRoot: folder, data: language)
-            } ?? []
+                    .init(atRoot: folder, data: language, log: log)
+            }
         // All properties initialized
         guard !languages.isEmpty else {
-            log.add(error: "No languages found", source: source)
+            log.error("No languages found", source: source)
+            return nil
+        }
+
+        guard isValid else {
             return nil
         }
 
         files.add(page: path, id: id)
-        self.readElements(in: folder, source: nil)
+        self.readElements(in: folder, source: nil, log: log)
     }
 
-    mutating func readElements(in folder: URL, source: String?) {
+    mutating func readElements(in folder: URL, source: String?, log: MetadataInfoLogger) {
         let subFolders: [URL]
         do {
             subFolders = try FileManager.default
                 .contentsOfDirectory(at: folder, includingPropertiesForKeys: [.isDirectoryKey])
                 .filter { $0.isDirectory }
         } catch {
-            log.add(error: "Failed to read subfolders", source: source ?? "root", error: error)
+            log.error("Failed to read subfolders: \(error)", source: source ?? "root")
             return
         }
         self.elements = subFolders.compactMap { subFolder in
             let s = (source.unwrapped { $0 + "/" } ?? "") + subFolder.lastPathComponent
-            return Element(parent: self, folder: subFolder, path: s)
+            return Element(parent: self, folder: subFolder, path: s, log: log)
         }
     }
 
-    init?(parent: Element, folder: URL, path: String) {
+    init?(parent: Element, folder: URL, path: String, log: MetadataInfoLogger) {
         self.inputFolder = folder
         self.path = path
 
         let source = path + "/" + GenericMetadata.metadataFileName
-        guard let metadata = GenericMetadata(source: source) else {
+        guard let metadata = GenericMetadata(source: source, log: log) else {
             return nil
         }
 
+        var isValid = true
+
         self.id = metadata.customId ?? folder.lastPathComponent
         self.author = metadata.author ?? parent.author
-        self.topBarTitle = log
-            .unused(metadata.topBarTitle, "topBarTitle", source: source) ?? parent.topBarTitle
-        let date = log.date(from: metadata.date, property: "date", source: source).ifNil {
-            if !parent.useManualSorting {
-                log.add(error: "No 'date', but parent defines 'useManualSorting' = false", source: source)
-            }
-        }
-        self.date = date
-        self.endDate = log.date(from: metadata.endDate, property: "endDate", source: source).ifNotNil {
-            if date == nil {
-                log.add(warning: "Set 'endDate', but no 'date'", source: source)
-            }
-        }
-        let state = log.state(metadata.state, source: source)
-        self.state = state
-        self.sortIndex = metadata.sortIndex.ifNil {
-            if state != .hidden, parent.useManualSorting {
-                log.add(error: "No 'sortIndex', but parent defines 'useManualSorting' = true", source: source)
-            }
-        }
+        self.topBarTitle = log.unused(metadata.topBarTitle, "topBarTitle", source: source)
+        self.date = metadata.date.unwrapped { log.cast($0, "date", source: source) }
+        self.endDate = metadata.date.unwrapped { log.cast($0, "endDate", source: source) }
+        self.state = log.cast(metadata.state, "state", source: source)
+        self.sortIndex = metadata.sortIndex
         // TODO: Propagate external files from the parent if subpath matches?
         self.externalFiles = Element.rootPaths(for: metadata.externalFiles, path: path)
         self.requiredFiles = Element.rootPaths(for: metadata.requiredFiles, path: path)
         self.images = metadata.images?.compactMap { ManualImage(input: $0, path: path) } ?? []
         self.thumbnailPath = metadata.thumbnailPath ?? Element.defaultThumbnailName
-        self.thumbnailStyle = log.thumbnailStyle(metadata.thumbnailStyle, source: source)
+        self.thumbnailStyle = log.cast(metadata.thumbnailStyle, "thumbnailStyle", source: source)
         self.useManualSorting = metadata.useManualSorting ?? false
         self.overviewItemCount = metadata.overviewItemCount ?? parent.overviewItemCount
-        self.headerType = log.headerType(metadata.headerType, source: source)
+        self.headerType = log.cast(metadata.headerType, "headerType", source: source)
+        self.showMostRecentSection = metadata.showMostRecentSection ?? false
         self.languages = parent.languages.compactMap { parentData in
             guard let data = metadata.languages?.first(where: { $0.language == parentData.language }) else {
-                log.add(info: "Language '\(parentData.language)' not found", source: source)
+                log.warning("Language '\(parentData.language)' not found", source: source)
                 return nil
             }
-            return .init(folder: folder, data: data, source: source, parent: parentData)
+            return .init(folder: folder, data: data, source: source, parent: parentData, log: log)
         }
         // Check that each 'language' tag is present, and that all languages appear in the parent
-        log.required(metadata.languages, name: "languages", source: source)?
-            .compactMap { log.required($0.language, name: "language", source: source) }
+        log.required(metadata.languages, name: "languages", source: source, &isValid)
+            .compactMap { log.required($0.language, name: "language", source: source, &isValid) }
             .filter { language in
                 !parent.languages.contains { $0.language == language }
             }
             .forEach {
-                log.add(warning: "Language '\($0)' not found in parent, so not generated", source: source)
+                log.warning("Language '\($0)' not found in parent, so not generated", source: source)
             }
 
         // All properties initialized
 
+        if self.date == nil, !parent.useManualSorting {
+            log.error("No 'date', but parent defines 'useManualSorting' = false", source: source)
+        }
+        if date == nil {
+            log.unused(self.endDate, "endDate", source: source)
+        }
+        if self.sortIndex == nil, state != .hidden, parent.useManualSorting {
+            log.error("No 'sortIndex', but parent defines 'useManualSorting' = true", source: source)
+        }
+
+        guard isValid else {
+            return nil
+        }
+
         files.add(page: path, id: id)
-        self.readElements(in: folder, source: path)
+        self.readElements(in: folder, source: path, log: log)
     }
 }
 
diff --git a/Sources/Generator/Content/GenericMetadata+Localized.swift b/Sources/Generator/Content/GenericMetadata+Localized.swift
index a50d1f0..010699d 100644
--- a/Sources/Generator/Content/GenericMetadata+Localized.swift
+++ b/Sources/Generator/Content/GenericMetadata+Localized.swift
@@ -14,8 +14,8 @@ extension GenericMetadata {
         let language: String?
 
         /**
-         - Note: This field is mandatory
          The title used in the page header.
+         - Note: This field is mandatory
          */
         let title: String?
 
diff --git a/Sources/Generator/Content/GenericMetadata.swift b/Sources/Generator/Content/GenericMetadata.swift
index a1afd84..9954905 100644
--- a/Sources/Generator/Content/GenericMetadata.swift
+++ b/Sources/Generator/Content/GenericMetadata.swift
@@ -169,8 +169,8 @@ extension GenericMetadata {
      - Note: The decoding routine also checks for unknown properties, and writes them to the output.
      - Note: Uses global objects
      */
-    init?(source: String) {
-        guard let data = files.dataOfOptionalFile(atPath: source, source: source) else {
+    init?(source: String, log: MetadataInfoLogger) {
+        guard let data = log.readPotentialMetadata(atPath: source, source: source) else {
             return nil
         }
 
@@ -196,8 +196,7 @@ extension GenericMetadata {
         do {
             self = try decoder.decode(from: data)
         } catch {
-            print("Here \(data)")
-            log.failedToOpen(GenericMetadata.metadataFileName, requiredBy: source, error: error)
+            log.failedToDecodeMetadata(source: source, error: error)
             return nil
         }
     }
diff --git a/Sources/Generator/Content/HeaderType.swift b/Sources/Generator/Content/HeaderType.swift
index 4a14837..c344bde 100644
--- a/Sources/Generator/Content/HeaderType.swift
+++ b/Sources/Generator/Content/HeaderType.swift
@@ -17,3 +17,19 @@ enum HeaderType: String {
      */
     case none
 }
+
+extension HeaderType: StringProperty {
+
+    init?(_ value: String) {
+        self.init(rawValue: value)
+    }
+
+    static var castFailureReason: String {
+        "Header type must be 'left', 'center' or 'none'"
+    }
+}
+
+extension HeaderType: DefaultValueProvider {
+
+    static var defaultValue: HeaderType { .left }
+}
diff --git a/Sources/Generator/Content/PageState.swift b/Sources/Generator/Content/PageState.swift
index 2762285..b0a5faa 100644
--- a/Sources/Generator/Content/PageState.swift
+++ b/Sources/Generator/Content/PageState.swift
@@ -39,3 +39,19 @@ extension PageState {
         }
     }
 }
+
+extension PageState: StringProperty {
+
+    init?(_ value: String) {
+        self.init(rawValue: value)
+    }
+
+    static var castFailureReason: String {
+        "Page state must be 'standard', 'draft' or 'hidden'"
+    }
+}
+
+extension PageState: DefaultValueProvider {
+
+    static var defaultValue: PageState { .standard }
+}
diff --git a/Sources/Generator/Content/StringProperty.swift b/Sources/Generator/Content/StringProperty.swift
new file mode 100644
index 0000000..0ec33c5
--- /dev/null
+++ b/Sources/Generator/Content/StringProperty.swift
@@ -0,0 +1,8 @@
+import Foundation
+
+protocol StringProperty {
+
+    init?(_ value: String)
+
+    static var castFailureReason: String { get }
+}
diff --git a/Sources/Generator/Content/ThumbnailStyle.swift b/Sources/Generator/Content/ThumbnailStyle.swift
index 2f439a7..5836e25 100644
--- a/Sources/Generator/Content/ThumbnailStyle.swift
+++ b/Sources/Generator/Content/ThumbnailStyle.swift
@@ -33,3 +33,19 @@ enum ThumbnailStyle: String, CaseIterable {
 extension ThumbnailStyle: Codable {
 
 }
+
+extension ThumbnailStyle: StringProperty {
+
+    init?(_ value: String) {
+        self.init(rawValue: value)
+    }
+
+    static var castFailureReason: String {
+        "Thumbnail style must be 'large', 'square' or 'small'"
+    }
+}
+
+extension ThumbnailStyle: DefaultValueProvider {
+
+    static var defaultValue: ThumbnailStyle { .large }
+}
diff --git a/Sources/Generator/Extensions/Array+Extensions.swift b/Sources/Generator/Extensions/Array+Extensions.swift
new file mode 100644
index 0000000..d52dca1
--- /dev/null
+++ b/Sources/Generator/Extensions/Array+Extensions.swift
@@ -0,0 +1,6 @@
+import Foundation
+
+extension Array: DefaultValueProvider {
+
+    static var defaultValue: Array<Element> { [] }
+}
diff --git a/Sources/Generator/Extensions/Bool+Extensions.swift b/Sources/Generator/Extensions/Bool+Extensions.swift
new file mode 100644
index 0000000..bd2966e
--- /dev/null
+++ b/Sources/Generator/Extensions/Bool+Extensions.swift
@@ -0,0 +1,6 @@
+import Foundation
+
+extension Bool: DefaultValueProvider {
+
+    static var defaultValue: Bool { true }
+}
diff --git a/Sources/Generator/Extensions/Date+Extensions.swift b/Sources/Generator/Extensions/Date+Extensions.swift
new file mode 100644
index 0000000..6dcf757
--- /dev/null
+++ b/Sources/Generator/Extensions/Date+Extensions.swift
@@ -0,0 +1,26 @@
+import Foundation
+
+extension Date: StringProperty {
+
+    private static let metadataDate: DateFormatter = {
+        let df = DateFormatter()
+        df.dateFormat = "dd.MM.yy"
+        return df
+    }()
+
+    init?(_ value: String) {
+        guard let date = Date.metadataDate.date(from: value) else {
+            return nil
+        }
+        self =  date
+    }
+
+    static var castFailureReason: String {
+        "Date string format must be 'dd.MM.yy'"
+    }
+}
+
+extension Date: DefaultValueProvider {
+
+    static var defaultValue: Date { .init() }
+}
diff --git a/Sources/Generator/Extensions/Int+Extensions.swift b/Sources/Generator/Extensions/Int+Extensions.swift
new file mode 100644
index 0000000..af732f0
--- /dev/null
+++ b/Sources/Generator/Extensions/Int+Extensions.swift
@@ -0,0 +1,13 @@
+import Foundation
+
+extension Int: StringProperty {
+
+    static var castFailureReason: String {
+        "The string was not a valid integer"
+    }
+}
+
+extension Int: DefaultValueProvider {
+
+    static var defaultValue: Int { 0 }
+}
diff --git a/Sources/Generator/Extensions/Optional+Extensions.swift b/Sources/Generator/Extensions/Optional+Extensions.swift
index c280067..1f94571 100644
--- a/Sources/Generator/Extensions/Optional+Extensions.swift
+++ b/Sources/Generator/Extensions/Optional+Extensions.swift
@@ -3,7 +3,7 @@ import Metal
 
 extension Optional {
 
-    func unwrapped<T>(_ closure: (Wrapped) -> T) -> T? {
+    func unwrapped<T>(_ closure: (Wrapped) -> T?) -> T? {
         if case let .some(value) = self {
             return closure(value)
         }
diff --git a/Sources/Generator/Extensions/String+Extensions.swift b/Sources/Generator/Extensions/String+Extensions.swift
index 5cb1335..9bcdde0 100644
--- a/Sources/Generator/Extensions/String+Extensions.swift
+++ b/Sources/Generator/Extensions/String+Extensions.swift
@@ -79,3 +79,8 @@ extension String {
         try data(using: .utf8)!.createFolderAndWrite(to: url)
     }
 }
+
+extension String: DefaultValueProvider {
+
+    static var defaultValue: String { "" }
+}
diff --git a/Sources/Generator/Files/FileSystem.swift b/Sources/Generator/Files/FileSystem.swift
index 021d8ea..2cfa5fb 100644
--- a/Sources/Generator/Files/FileSystem.swift
+++ b/Sources/Generator/Files/FileSystem.swift
@@ -18,6 +18,8 @@ final class FileSystem {
         input.appendingPathComponent(FileSystem.tempFileName)
     }
 
+    let generatorInfoFolder: URL
+
     /**
      All files which should be copied to the output folder
      */
@@ -70,7 +72,7 @@ final class FileSystem {
         self.input = input
         self.output = output
         self.images = .init(input: input, output: output)
-
+        self.generatorInfoFolder = input.appendingPathComponent("run")
     }
 
     func urlInOutputFolder(_ path: String) -> URL {
@@ -100,20 +102,6 @@ final class FileSystem {
         }
     }
 
-    func dataOfOptionalFile(atPath path: String, source: String) -> Data? {
-        let url = input.appendingPathComponent(path)
-        guard exists(url) else {
-            return nil
-        }
-
-        do {
-            return try Data(contentsOf: url)
-        } catch {
-            log.failedToOpen(path, requiredBy: source, error: error)
-            return nil
-        }
-    }
-
     func contentOfOptionalFile(atPath path: String, source: String, createEmptyFileIfMissing: Bool = false) -> String? {
         let url = input.appendingPathComponent(path)
         guard exists(url) else {
diff --git a/Sources/Generator/Files/ValidationLog.swift b/Sources/Generator/Files/ValidationLog.swift
index ae44739..3e8e3ef 100644
--- a/Sources/Generator/Files/ValidationLog.swift
+++ b/Sources/Generator/Files/ValidationLog.swift
@@ -46,119 +46,7 @@ final class ValidationLog {
         add(info: .init(reason: reason, source: source, error: error))
     }
 
-    @discardableResult
-    func unused<T, R>(_ value: Optional<T>, _ name: String, source: String) -> Optional<R> {
-        if value != nil {
-            add(info: "Unused property '\(name)'", source: source)
-        }
-        return nil
-    }
-
-    func unknown(property: String, source: String) {
-        add(info: "Unknown property '\(property)'", source: source)
-    }
-
-    func required<T>(_ value: Optional<T>, name: String, source: String) -> Optional<T> {
-        guard let value = value else {
-            add(error: "Missing property '\(name)'", source: source)
-            return nil
-        }
-        return value
-    }
-
-    func unexpected<T>(_ value: Optional<T>, name: String, source: String) -> Optional<T> {
-        if let value = value {
-            add(error: "Unexpected property '\(name)' = '\(value)'", source: source)
-            return nil
-        }
-        return nil
-    }
-
-    func missing(_ file: String, requiredBy source: String) {
-        print("[ERROR] Missing file '\(file)' required by \(source)")
-    }
-
     func failedToOpen(_ file: String, requiredBy source: String, error: Error?) {
         print("[ERROR] Failed to open file '\(file)' required by \(source): \(error?.localizedDescription ?? "No error provided")")
     }
-
-    func state(_ raw: String?, source: String) -> PageState {
-        guard let raw = raw else {
-            return .standard
-        }
-        guard let state = PageState(rawValue: raw) else {
-            add(warning: "Invalid 'state' '\(raw)', using 'standard'", source: source)
-            return .standard
-        }
-        return state
-    }
-
-    func headerType(_ raw: String?, source: String) -> HeaderType {
-        guard let raw = raw else {
-            return .left
-        }
-        guard let type = HeaderType(rawValue: raw) else {
-            add(warning: "Invalid 'headerType' '\(raw)', using 'left'", source: source)
-            return .left
-        }
-        return type
-    }
-
-    func thumbnailStyle(_ raw: String?, source: String) -> ThumbnailStyle {
-        guard let raw = raw else {
-            return .large
-        }
-        guard let style = ThumbnailStyle(rawValue: raw) else {
-            add(warning: "Invalid 'thumbnailStyle' '\(raw)', using 'large'", source: source)
-            return .large
-        }
-        return style
-    }
-
-    func linkPreviewThumbnail(customFile: String?, for language: String, in folder: URL, source: String) -> String? {
-        guard let customFile = customFile else {
-            return nil
-        }
-        let customFileUrl: URL
-        if customFile.starts(with: "/") {
-            customFileUrl = URL(fileURLWithPath: customFile)
-        } else {
-            customFileUrl = folder.appendingPathComponent(customFile)
-        }
-        guard customFileUrl.exists else {
-            missing(customFile, requiredBy: "property 'linkPreviewImage' in metadata of \(source)")
-            return nil
-        }
-        return customFile
-    }
-
-    func moreLinkText(_ elementText: String?, parent parentText: String?, source: String) -> String {
-        if let elementText = elementText {
-            return elementText
-        }
-        let standard = Element.LocalizedMetadata.moreLinkDefaultText
-        guard let parentText = parentText, parentText != standard else {
-            add(error: "Missing property 'moreLinkText'", source: source)
-            return standard
-        }
-
-        return parentText
-    }
-
-    func date(from string: String?, property: String, source: String) -> Date? {
-        guard let string = string else {
-            return nil
-        }
-        guard let date = ValidationLog.metadataDate.date(from: string) else {
-            add(warning: "Invalid date string '\(string)' for property '\(property)'", source: source)
-            return nil
-        }
-        return date
-    }
-
-    private static let metadataDate: DateFormatter = {
-        let df = DateFormatter()
-        df.dateFormat = "dd.MM.yy"
-        return df
-    }()
 }
diff --git a/Sources/Generator/Processing/MetadataInfoLogger.swift b/Sources/Generator/Processing/MetadataInfoLogger.swift
new file mode 100644
index 0000000..4baedc3
--- /dev/null
+++ b/Sources/Generator/Processing/MetadataInfoLogger.swift
@@ -0,0 +1,150 @@
+import Foundation
+
+final class MetadataInfoLogger {
+
+    private let input: URL
+
+    private var numberOfMetadataFiles = 0
+
+    private var unusedProperties: [(name: String, source: String)] = []
+
+    private var invalidProperties: [(name: String, source: String, reason: String)] = []
+
+    private var unknownProperties: [(name: String, source: String)] = []
+
+    private var missingProperties: [(name: String, source: String)] = []
+
+    private var unreadableMetadata: [(source: String, error: Error)] = []
+
+    private var warnings: [(source: String, message: String)] = []
+
+    private var errors: [(source: String, message: String)] = []
+
+    init(input: URL) {
+        self.input = input
+    }
+
+    /**
+     Adds an info message if a value is set for an unused property.
+     - Note: Unused properties do not cause an element to be skipped.
+     */
+    @discardableResult
+    func unused<T>(_ value: Optional<T>, _ name: String, source: String) -> T where T: DefaultValueProvider {
+        if let value {
+            unusedProperties.append((name, source))
+            return value
+        }
+        return T.defaultValue
+    }
+
+    /**
+     Cast a string value to another value, and using a default in case of errors.
+     - Note: Invalid string values do not cause an element to be skipped.
+     */
+    func cast<T>(_ value: String, _ name: String, source: String) -> T where T: DefaultValueProvider, T: StringProperty {
+        guard let result = T.init(value) else {
+            invalidProperties.append((name: name, source: source, reason: T.castFailureReason))
+            return T.defaultValue
+        }
+        return result
+    }
+
+    /**
+     Cast a string value to another value, and using a default in case of errors or missing values.
+     - Note: Invalid string values do not cause an element to be skipped.
+     */
+    func cast<T>(_ value: String?, _ name: String, source: String) -> T where T: DefaultValueProvider, T: StringProperty {
+        guard let value else {
+            return T.defaultValue
+        }
+        guard let result = T.init(value) else {
+            invalidProperties.append((name: name, source: source, reason: T.castFailureReason))
+            return T.defaultValue
+        }
+        return result
+    }
+
+    /**
+     Cast the string value of an unused property to another value, and using a default in case of errors.
+     - Note: Invalid string values do not cause an element to be skipped.
+     */
+    func castUnused<R>(_ value: String?, _ name: String, source: String) -> R where R: DefaultValueProvider, R: StringProperty {
+        unused(value.unwrapped { cast($0, name, source: source) }, name, source: source)
+    }
+
+    /**
+     Note an unknown property.
+     - Note: Unknown properties do not cause an element to be skipped.
+     */
+    func unknown(property: String, source: String) {
+        unknownProperties.append((name: property, source: source))
+    }
+
+    /**
+     Ensure that a property is set, and aborting metadata decoding.
+     - Note: Missing required properties cause an element to be skipped.
+     */
+    func required<T>(_ value: T?, name: String, source: String, _ valid: inout Bool) -> T where T: DefaultValueProvider {
+        guard let value = value else {
+            missingProperties.append((name, source))
+            valid = false
+            return T.defaultValue
+        }
+        return value
+    }
+
+    func warning(_ message: String, source: String) {
+        warnings.append((source, message))
+    }
+
+    func error(_ message: String, source: String) {
+        errors.append((source, message))
+    }
+
+    func failedToDecodeMetadata(source: String, error: Error) {
+        unreadableMetadata.append((source, error))
+    }
+
+    func readPotentialMetadata(atPath path: String, source: String) -> Data? {
+        let url = input.appendingPathComponent(path)
+        guard url.exists else {
+            return nil
+        }
+
+        numberOfMetadataFiles += 1
+        printMetadataScanUpdate()
+        do {
+            return try Data(contentsOf: url)
+        } catch {
+            unreadableMetadata.append((source, error))
+            return nil
+        }
+    }
+
+    // MARK: Printing
+
+    private func printMetadataScanUpdate() {
+        print(String(format: "Scanning source files: %4d pages found     \r", numberOfMetadataFiles), terminator: "")
+    }
+
+    func printMetadataScanOverview() {
+        print("    Number of pages: \(numberOfMetadataFiles)")
+        print("   Unreadable files: \(unreadableMetadata.count)")
+        print("  Unused properties: \(unusedProperties.count)")
+        print(" Invalid properties: \(invalidProperties.count)")
+        print(" Unknown properties: \(unknownProperties.count)")
+        print(" Missing properties: \(missingProperties.count)")
+    }
+
+    func writeResultsToFile(in folder: URL) throws {
+        let url = folder.appendingPathComponent("Metadata issues.txt")
+        var lines = ["Unreadable files:"] + unreadableMetadata.map { "\($0.source): \($0.error)" }
+        lines += ["Unused properties:"] + unusedProperties.map { "\($0.source): \($0.name)" }
+        lines += ["Invalid properties:"] + invalidProperties.map { "\($0.source): \($0.name) (\($0.reason))" }
+        lines += ["Unknown properties:"] + unknownProperties.map { "\($0.source): \($0.name)" }
+        lines += ["Missing properties:"] + missingProperties.map { "\($0.source): \($0.name)" }
+
+        let data = lines.joined(separator: "\n").data(using: .utf8)
+        try data?.createFolderAndWrite(to: url)
+    }
+}
diff --git a/Sources/Generator/run.swift b/Sources/Generator/run.swift
index 64d9503..062417e 100644
--- a/Sources/Generator/run.swift
+++ b/Sources/Generator/run.swift
@@ -17,6 +17,16 @@ struct CHGenerator: ParsableCommand {
     }
 }
 
+private func loadSiteData(in folder: URL) throws -> Element? {
+    let log = MetadataInfoLogger(input: folder)
+    print("--- SOURCE FILES -----------------------------------")
+    let root = Element(atRoot: folder, log: log)
+    print("                                                    ")
+    log.printMetadataScanOverview()
+    try log.writeResultsToFile(in: files.generatorInfoFolder)
+    return root
+}
+
 private func generate(configPath: String) throws {
     let configUrl = URL(fileURLWithPath: configPath)
     let data = try Data(contentsOf: configUrl)
@@ -26,7 +36,8 @@ private func generate(configPath: String) throws {
         in: configuration.contentDirectory,
         to: configuration.outputDirectory)
 
-    siteRoot = Element(atRoot: configuration.contentDirectory)
+    // 2. Scan site elements
+    siteRoot = try loadSiteData(in: configuration.contentDirectory)
     guard siteRoot != nil else {
         return
     }