A custom Document Information Panel (DIP) fails to open and returns a schema error. The following screenshot is an example of where a once functioning DIP fails to load because of metadata that has been added incorrectly to the content type. The problem presents in SharePoint Online but is likely to be evident in an on premise implementation also.
When a DIP is customised it is ‘hard-coded’ to understand the metadata that is expected to be supplied by the library at runtime. Even the ordering of the fields within the library seems to be significant. When fields are added to a content type it causes the rendering of the DIP to fail. In this specific example two publishing fields had been injected into the content type by an external process. We are yet to determine what this process was but we know it wasn’t manually added.
As can be seen in the screenshot the fields that caused our issue were publishing fields whose display names are Scheduled Start Date and Scheduled End Date.
Switch off scheduled publishing
The two fields that are causing the problem are ‘sealed’ fields and thus cannot be manually deleted. In order to remove them the following process must be followed:
In the document library settings, go to versioning settings and set the following properties:
Go back to the document library settings and select the Manage Item Scheduling option. Switch this on and click OK. Note this will take you back to SITE settings not library settings. Press back twice to get back to the library settings and re-select the Manage Item Scheduling option, this time switch it off again!