Cannot edit Modern Design Pages after Update

Office 365 Groups – Rezepte für die Feiertage
9. Dezember 2019

If you can´t edit Modern Design Pages or you can´t add News Posts in SharePoint 2019 Modern Design after Updating to the October 2020 Cumulative-Update (CU). Try adding Safe Controls in your web.config to resolve the Error.

My Customers also get Errors like “Unable to get property ‘call’ of undefined or null reference” from the sp-pages-assembly.js.

The fix was to add the layouts Folder to the Safe Controls:

<SafeControl Src="~/_layouts/*" IncludeSubFolders="True" Safe="True" AllowRemoteDesigner="True" SafeAgainstScript="True" />

Hopefully, this could help you save time!