data of manifest.rdf could not be read

I have a form that had been working just fine, no changes to the computer, program updates. I can see the table no problem. When I try and use a form that is associated with that table I receive the error message:

Data of manifest.rdf could not be read

How do I fix this error?

I do have the exact same question. The message “Daten von manifest.rdf konnten nicht gelesen werden.” (in german) showed up when opening a form a few days ago and persisted since then. The database had been used for years and not been changed in any way. After clicking OK, the form opens as expected though. But I fear, there may be problems in the future with my database file… So I would not at all say that this error message is “not relevant” or “outdated”…