[Expression.Error] We cannot convert a value of type List to type Record.

Jimmy

Is this what you are after - I have removed the URL details

let
Source = Json.Document(Web.Contents("<REDACTED>")),
List = {1..Source[page_count]},
#"Converted to Table" = Table.FromList(List, Splitter.SplitByNothing(), null, null, ExtraValues.Error),
#"Changed Type" = Table.TransformColumnTypes(#"Converted to Table",{{"Column1", type text}}),
#"Invoked Custom Function" = Table.AddColumn(#"Changed Type", "Data", each getPage([Column1])),
#"Expanded Data" = Table.ExpandTableColumn(#"Invoked Custom Function", "Data", {"Column1.id", "Column1.type", "Column1.sourceId", "Column1.summary", "Column1.reference", "Column1.description", "Column1.statusId", "Column1.sourceSeverityId", "Column1.customSeverityId", "Column1.discoveryDate", "Column1.dueDate", "Column1.ownerId", "Column1.exploitabilityEase", "Column1.exploitAvailable", "Column1.sourceSeverity", "Column1.source", "Column1.closedDate", "Column1.destinationHostIp", "Column1.destinationHost", "Column1.solution", "Column1.categories", "Column1.keywords", "Column1.linkedPentests", "Column1.linkedRisks", "Column1.linkedActions", "Column1.status", "Column1.customSeverity", "Column1.owner", "Column1.customFields", "Column1._links"}, {"Data.Column1.id", "Data.Column1.type", "Data.Column1.sourceId", "Data.Column1.summary", "Data.Column1.reference", "Data.Column1.description", "Data.Column1.statusId", "Data.Column1.sourceSeverityId", "Data.Column1.customSeverityId", "Data.Column1.discoveryDate", "Data.Column1.dueDate", "Data.Column1.ownerId", "Data.Column1.exploitabilityEase", "Data.Column1.exploitAvailable", "Data.Column1.sourceSeverity", "Data.Column1.source", "Data.Column1.closedDate", "Data.Column1.destinationHostIp", "Data.Column1.destinationHost", "Data.Column1.solution", "Data.Column1.categories", "Data.Column1.keywords", "Data.Column1.linkedPentests", "Data.Column1.linkedRisks", "Data.Column1.linkedActions", "Data.Column1.status", "Data.Column1.customSeverity", "Data.Column1.owner", "Data.Column1.customFields", "Data.Column1._links"}),
#"Renamed Columns" = Table.RenameColumns(#"Expanded Data",{{"Data.Column1.type", "Type"}, {"Data.Column1.summary", "Summary"}, {"Data.Column1.description", "Description"}, {"Data.Column1.discoveryDate", "Discovery Date"}, {"Data.Column1.source", "Vuln-Source"}, {"Data.Column1.destinationHostIp", "IP Address"}, {"Data.Column1.destinationHost", "Hostname"}, {"Data.Column1.solution", "Recommendation"}, {"Data.Column1.status", "Status"}, {"Data.Column1.customSeverity", "<REDACTED> Severity"}}),
#"Expanded Data.Column1.customFields" = Table.ExpandRecordColumn(#"Renamed Columns", "Data.Column1.customFields", {"msTags", "ddFindingType", "ddFindingSource"}, {"Data.Column1.customFields.msTags", "Data.Column1.customFields.ddFindingType", "Data.Column1.customFields.ddFindingSource"}),
#"Renamed Columns1" = Table.RenameColumns(#"Expanded Data.Column1.customFields",{{"Data.Column1.customFields.ddFindingType", "Finding Type"}, {"Data.Column1.customFields.ddFindingSource", "Finding Source"}}),
#"Renamed Columns2" = Table.RenameColumns(#"Renamed Columns1",{{"Data.Column1.closedDate", "Closed Date"}}),
#"Changed Type1" = Table.TransformColumnTypes(#"Renamed Columns2",{{"Discovery Date", type datetime}, {"Data.Column1.customFields.msTags", type text}}),
#"Renamed Columns3" = Table.RenameColumns(#"Changed Type1",{{"Data.Column1.customFields.msTags", "Tags"}}),
#"Kept Errors" = Table.SelectRowsWithErrors(#"Renamed Columns3", {"Finding Source"})
in
#"Kept Errors"