Acces encrypted files after database loss

Dear ownCloud team i have currently a major issue accessing my encrypted files after a database loss.
Unfortunately, after a database crash i'm unable to access my encrypted files. No Backup of the database is available.

Due to a disk failure on my system drive my server went corrupted and i had to reinstall everything.
The Data folder was not affected by the failure as it is on a separate partition.

After the installation i created a new owncloud with the same owncloud Version and used the same config as before. I had a backup of my config file but not from database.

After the initial configuration of the server and the users with the same passwords i attached the Datafolder and started a manual filescan over occ.

All files are shown in the web interface but i am not able to open any file.

Steps to reproduce
1. Delete Database
2. Setup new Owncloud instance with old config file
3. Recreate Users with same Password
4. Attache Datafolder and Import files with occ files:scan
5. Try to access files

Expected behaviour
Files should be opened as expected

Actual behaviour
Nothing happens files will not be opened. No error message in log.
PDF Error Message: Unexpected server response (0) while retrieving PDF

Server configuration
Operating system: debian 7
Web server: apache 2
Database: mysql
PHP version: 5.6.28-1
ownCloud version (see ownCloud admin page):
Updated from an older ownCloud or fresh install: fresh
Special configuration (external storage, external authentication, reverse proxy, server-side-encryption): data an separate partition

ownCloud log (data/owncloud.log)

No errors are logged

Am I missing something? Thank you for your support.

There is a signature in each encrypted file created with information of the database. So you can only restore it, when you somehow ignore the signature. I tried this recently with a Nextcloud setup (encryption module is probably still very similar) but it wasn't that easy. Perhaps you are more lucky:

If not, you could try to create a feature request to provide a recovery tool.

Thank you for the hint. Just tested it. But in OC 8.2 i don't find any signature check... Can you tell me how you modified the signature check?

Could be that this feature was just added in OC 9.0, so it isn't relevant for you. But in this case you should be able to read your files (supposing that you have all the key files). Did you check other files, sometimes the pdfviewer was a bit problematic in some versions.

Thank for your reply. I don't know why it doesn't work. Will try again with different settings and configurations....