This webpart was working on a classic Publishing site. Recently, it started throwing this error message:
Error details: Error: Error initializing application. Error: TypeError: Cannot read property 'Content' of undefined
On an article page the error message is different:
Error details: Error: Error initializing application. Error: TypeError: Cannot read property 'CanvasContent1' of null
When I place this webpart on a modern page, it works without problems but I do not have the luxury to serve it on a modern page. Another strange thing is that it has to be on the rootweb. It does not work under sub webs anymore.(I am thinking something has changed on microsoft recently...)
I can not even debug it because it works in the local workbench and hosted workbench.
Any ideas on how to solve this? or troubleshooting tips?