Trying to import an XML backup into Confluence, we might have the below issue:
Couldn't find the specific steps to reproduce it but certain XML backups have this issue. This has including been documented here.
This looks like a issue with the entities.xml file, and can be fixed by running the below command on Terminal:
The attached space export file was manually modified to add the invalid \xFFFF character into entities.xml. Entering the character through the editor is not possible.