Fails to decrypt encrypted files after upgrading to 10.0.2

Just upgraded to 10.0.2 from 10.0.0 and now I cannot download or open encrypted files for one or two Owncloud folders. Other folders works but not one or two.

owncloud.log says "Can not decrypt this file, probably this is a shared file. Please ask the file owner to reshare the file with you."

When checking encryption keys in the data storage, no key files have a newer file date, so the storage is untouched since upgrade. The actual files are there too, unable to be decrypted.

Any tips how to get my files back? I'm stuck.

Just noticed that the encryption module could be deactivated (not sure) after upgrading to 10.0.0. So when upgrading to 10.0.2 encryption was not upgraded?

How did you upgrade?
Yes, you will need to install the encryption app from the marketplace and enable it. Did you do a backup prior to upgrading?