[BUG] Unable to restore backup due to `repo.xml`

[marmoure]

While trying to restore a backup in elemental I got this error log

Finished restore of backup.
------------------------------------
Problems occurred found during restore:
WARN: Failed to restore resource 'repo.xml'
from file 'C:\Users\z\AppData\Local\Temp\exist-db-temp-file-manager-2230822812163341171\exist-db-temp-7502612767840769060.tmp#apps/eXide/repo.xml'.
Reason: The XML parser reported a problem: fatal error at (259,11) : The element type "change" must be terminated by the matching end-tag "</change>".


If you restored collections inside /db/apps, you may want
to rebuild the application repository. To do so, run the following query
as admin:

import module namespace repair="http://exist-db.org/xquery/repo/repair"
at "resource:org/exist/xquery/modules/expathrepo/repair.xql";
repair:clean-all(),
repair:repair()

And it seems like the issue is coming from one of the apps repo.xml , here's the exact lines that caused the issue

        <change xmlns:repo="http://exist-db.org/xquery/repo" version="2.0.9">
            <ul xmlns="http://www.w3.org/1999/xhtml">
                <li>Remove size limits for documents which can be validated by the editor. Live error messages
                will be shown even for large documents/XQueries.</li>
                <li>Fixed navigation in edit history.</li>
            </ul>
        </repo:change>

The backup process thinks the XML is invalid due to the mismatch in <change> and </repo:change> tags.

[adamretter]

Where was the backup created from - eXist-db or Elemental, and which version of that please? Also which process was used to create the backup please?

Then, which version of Elemental was used to try and restore the backup please?

[marmoure]

Sorry @adamretter I wanted to dig deeper into this, here's how to reproduce it

1. Create a backup from Elemental using the backup in the dashboard

full20250803-1905.zip
2. Get a clean instance of Elemental and start it bin/startup.sh
3. Unzip the backup
4. Restore it using backup.sh -r path/db/__contents__.xml
You get the message above.

I used the latest release 7.2.1 from GitHub.

[marmoure]

@adamretter when following the path in the error message It pointed to eXide repo.xml to that mismatching change tag.

[adamretter]

I looked into this a little. The problem seems to be introduced into the file /db/apps/eXide/repo.xml when it is serialized from the database to disk as part of the Backup process. The problem in the serialized file starts at line 253, and looks like this:

<change xmlns:repo="http://exist-db.org/xquery/repo" version="2.0.9">
    <ul xmlns="http://www.w3.org/1999/xhtml">
        <li>Remove size limits for documents which can be validated by the editor. Live error messages
        will be shown even for large documents/XQueries.</li>
        <li>Fixed navigation in edit history.</li>
    </ul>
</repo:change>

Notethe starting <change tag but closing </repo:change> tag!
Note that it is also interesting this starts with the change description for eXide version2.0.9, there are newer change descriptions before that which are serialized just fine.

Further observations:

1. The issue occurs when you perform a backup from the Dashboard. The Dashboard eventually calls the org.exist.backup.SystemExport class to perform the backup.
2. If you perform a backup from the JAC (Java Admin Client), then the serialized /db/apps/eXide/repo.xml appears to be correct. This requests a backup via the XML:DB API over either local (embedded in-JVM) or remote (XML-RPC). This uses the org.exist.backup.Backup class to perform the backup.
3. The repo.xml file of eXide as it stands before it is imported into the database, which valid and well-formed, has some peculiarities:
   1. An unnecessary namespace (and prefix) declaration for the <permissions element - https://github.com/eXist-db/eXide/blob/7b2e802b847489806b8c239f087d2adea7044763/repo.xml#L13
   2. After a bunch of change descriptions, there are some further change descriptions that have an unnecessary prefix on their element names (i.e. <repo:change instead of <change) - https://github.com/eXist-db/eXide/blob/7b2e802b847489806b8c239f087d2adea7044763/repo.xml#L248 . NOTE it seems like an unlikely coincidence that this starts at eXide version 2.0.9 (see note above).

Next steps:

1. Investigate how the valid repo.xml file is parsed by Elemental and stored into the database, paying attention to the unnecessary namespace declaration and prefixes of the <permissions and <repo:change elements.
2. Investigate how the valid repo.xml file once in the database is serialized out during a backup process (from org.exist.backup.SystemExport), and why the backup process is introducing an error in the serialized XML.