Backup/Restore: ZIP file seems to be damaged

[kreativkonzept]

A couple of months ago our Confluence installation suddenly stopped working and the setup screen appeared. When trying to restore from backup we receive the following error:

The zip file did not contain an entry 'exportDescriptor.properties'. It did not contain any files, or was not a valid zip file.

I verified permissions and tried to unzip on the host itself which leads to this error:

root@Confluence:~# unzip backup-2022_06_04.zip
Archive: backup-2022_06_04.zip
End-of-central-directory signature not found. Either this file is not
a zipfile, or it constitutes one disk of a multi-part archive. In the
latter case the central directory and zipfile comment will be found on
the last disk(s) of this archive.
unzip: cannot find zipfile directory in one of backup-2022_06_04.zip or
backup-2022_06_04.zip.zip, and cannot find backup-2022_06_04.zip.ZIP, period.

I tried to repair with zip -FF but doesn't work either

root@Confluence:~# zip -FF backup-2022_06_04 --out backup-2022_06_04-fixed
Fix archive (-FF) - salvage what can
zip warning: Missing end (EOCDR) signature - either this archive
is not readable or the end is damaged
Is this a single-disk archive? (y/n): y
Assuming single-disk archive
Scanning for entries...
zip warning: unexpected signature 50 4b 0b 01 on disk 0 at 20755827

zip warning: skipping this signature...
zip warning: unexpected signature 50 4b 01 0d on disk 0 at 23903954

zip warning: skipping this signature...
zip warning: unexpected signature 50 4b 04 0d on disk 0 at 25603292

zip warning: skipping this signature...
zip warning: unexpected signature 50 4b 06 08 on disk 0 at 36544577

zip warning: skipping this signature...
zip warning: unexpected signature 50 4b 02 00 on disk 0 at 40826644

zip warning: skipping this signature...
zip warning: unexpected signature 50 4b 0c 04 on disk 0 at 58581204

zip warning: skipping this signature...
zip warning: unexpected signature 50 4b 0a 05 on disk 0 at 73089494

zip warning: skipping this signature...
zip warning: unexpected signature 50 4b 09 07 on disk 0 at 117674888

zip warning: skipping this signature...
zip warning: unexpected signature 50 4b 06 02 on disk 0 at 134198024

zip warning: skipping this signature...
zip warning: unexpected signature 50 4b 0b 07 on disk 0 at 169823591

zip warning: skipping this signature...
zip warning: unexpected signature 50 4b 01 0b on disk 0 at 172830129

zip warning: skipping this signature...
zip warning: unexpected signature 50 4b 06 0b on disk 0 at 191052363

zip warning: skipping this signature...
zip warning: unexpected signature 50 4b 08 02 on disk 0 at 192287937

zip warning: skipping this signature...
zip warning: unexpected signature 50 4b 07 03 on disk 0 at 224682074

zip warning: skipping this signature...
zip warning: unexpected signature 50 4b 0e 0b on disk 0 at 256697364

zip warning: skipping this signature...
zip warning: unexpected signature 50 4b 0c 00 on disk 0 at 297408042

zip warning: skipping this signature...
zip warning: unexpected signature 50 4b 0d 0f on disk 0 at 298180855

zip warning: skipping this signature...
zip warning: unexpected signature 50 4b 0b 08 on disk 0 at 314446725

zip warning: skipping this signature...
zip warning: unexpected signature 50 4b 0e 0c on disk 0 at 317010121

zip warning: skipping this signature...
zip warning: unexpected signature 50 4b 0c 09 on disk 0 at 317579187

zip warning: skipping this signature...
zip warning: unexpected signature 50 4b 07 07 on disk 0 at 320896993

zip warning: skipping this signature...
zip warning: unexpected signature 50 4b 0e 03 on disk 0 at 365283251

zip warning: skipping this signature...
zip warning: unexpected signature 50 4b 08 06 on disk 0 at 394759121

zip warning: skipping this signature...
zip warning: unexpected signature 50 4b 0f 0b on disk 0 at 398863952

zip warning: skipping this signature...
zip warning: unexpected signature 50 4b 0d 05 on disk 0 at 424645244

zip warning: skipping this signature...
zip warning: unexpected signature 50 4b 0b 00 on disk 0 at 456744597

zip warning: skipping this signature...
zip warning: zip file empty

However, all the 150+ backups have a disk size of roughly 500MB. They are, however, all appended with ".locked". Is there any chance of recovering the data?

[Yao Chang Hsu]

If you have another confluence instance, you can try restore it in another. 

[kreativkonzept]

How would that fix the corrupted zip-files?

[Yao Chang Hsu]

You can ask atlassian support team, and I suggest alternative method for you to choose.

And you must use the same version confluence to restore it in another instance.

[kreativkonzept]

I really appreciate you taking time to solve my problem. However, since the database is empty and the backup file damaged I fail to understand how a second instance of confluence helps in these circumstances. If my source for a restore is damaged I believe I have to fix the source first.

[Gonchik Tsymzhitov]

The main cause in my situation was issue with JRE