We're trying to figure out what is the cause of a backend error for our site on Umbraco version 13.5.2 When opening any content node we see a message along the lines of: > Server error: Contact administrator, see log for full details. > Failed to retrieve data for a node's menu 28589 The id changes depending on which node we open. There are no log entires for this error for some reason. Check the network request that files in devtools we see it's for, for example:

/umbraco/backoffice/umbracotrees/contenttree/GetMenu?id=28589&application=content&tree=content&use=main&culture=

This fails with error 500. The payload is the query parameter and the response is:

{
  "ExceptionMessage": "One or more errors occurred. ('1.0' is an unexpected token. The expected token is '\"' or '''. Line 1, position 15.)",
  "ExceptionType": null,
  "StackTrace": null
}

Any idea how to fix or what's wrong? It sounds like parsing something, somewhere? But without logs, no idea where this is happening. https://cdn.discordapp.com/attachments/1327232119214309416/1327232119746859009/image.png?ex=678250bc&is=6780ff3c&hm=655c0014341e28d2258a19ede3b3847c0c949d5f4eff0e9b1b80e6f5179737b2&

This could potentially happen when you change the type of an existing property. For instance, if you have a property with an alias 'test' which is just a textbox and you use this property on a content node and save that conteent node. If you now change the property 'test' to a multinode tree picker, you could end up with the issue you are having. Because in the database (because the alias didn't change) the property with alias 'test', just contains a simple string, because it was a textbox before. But Umbraco tries to parse it as a multinode tree picker, because that's now the type of that property. That's my theory. In general, I don't want to change the types of properties once they are in use. Did you recently change the type of a property?

Not that I know of, but this is a good guess I would bet on in this case. It is in a dev environment where some dev probably could've tried something experimental. Thank you.