I found an issue in the migration script while running it on dry-mode, for instance for eswiki this was the output:

There are changes:
Additions:
{
    "Mentors": {
        "1": {
            "awayTimestamp": "20251118130934"
        },
        "2" {
            "awayTimestamp": "20260623200305"
        }
    }
}
Deletions:
{
    "Mentors": {
        "1": {
            "awayTimestamp": "2025-11-18T13:09:34Z"
        }
    }
}

I forgot to update the script in T406701 and now it would save the values again using unix format rather than ISO. Providing a fix before running.

Change #1206894 had a related patch set uploaded (by Sergio Gimeno; author: Sergio Gimeno):

[mediawiki/extensions/GrowthExperiments@master] fix(MigrateMentorStatusAway): ensure migration respects date format

https://gerrit.wikimedia.org/r/1206894

Change #1206894 merged by jenkins-bot:

[mediawiki/extensions/GrowthExperiments@master] fix(MigrateMentorStatusAway): ensure migration respects date format

https://gerrit.wikimedia.org/r/1206894

Change #1207118 had a related patch set uploaded (by Sergio Gimeno; author: Sergio Gimeno):

[mediawiki/extensions/GrowthExperiments@wmf/1.46.0-wmf.3] fix(MigrateMentorStatusAway): ensure migration respects date format

https://gerrit.wikimedia.org/r/1207118

Change #1207118 merged by jenkins-bot:

[mediawiki/extensions/GrowthExperiments@wmf/1.46.0-wmf.3] fix(MigrateMentorStatusAway): ensure migration respects date format

https://gerrit.wikimedia.org/r/1207118

Mentioned in SAL (#wikimedia-operations) [2025-11-19T14:30:50Z] <sgimeno@deploy2002> Started scap sync-world: Backport for [[gerrit:1206936|fix(ReviseToneExperimentInteractionLogger): prevent breaking homepage for unsampled users (T405177)]], [[gerrit:1207118|fix(MigrateMentorStatusAway): ensure migration respects date format (T409170)]]

Mentioned in SAL (#wikimedia-operations) [2025-11-19T14:35:28Z] <sgimeno@deploy2002> sgimeno: Backport for [[gerrit:1206936|fix(ReviseToneExperimentInteractionLogger): prevent breaking homepage for unsampled users (T405177)]], [[gerrit:1207118|fix(MigrateMentorStatusAway): ensure migration respects date format (T409170)]] synced to the testservers (see https://wikitech.wikimedia.org/wiki/Mwdebug). Changes can now be verified there.

Mentioned in SAL (#wikimedia-operations) [2025-11-19T14:40:00Z] <sgimeno@deploy2002> Finished scap sync-world: Backport for [[gerrit:1206936|fix(ReviseToneExperimentInteractionLogger): prevent breaking homepage for unsampled users (T405177)]], [[gerrit:1207118|fix(MigrateMentorStatusAway): ensure migration respects date format (T409170)]] (duration: 09m 09s)

Not sure why mwscript-k8s is stopping at afwiki when I run this:

sgimeno@deploy2002:~$ mwscript-k8s -f --comment="T409170" --dblist="growthexperiments" -- GrowthExperiments:migrateMentorStatusAway --dry-run
GrowthExperiments:migrateMentorStatusAway: Running on growthexperiments
-----------------------------------------------------------------
abwiki
-----------------------------------------------------------------
abwiki No mentors found in config, skipping migration.
-----------------------------------------------------------------
acewiki
-----------------------------------------------------------------
acewiki No mentors found in config, skipping migration.
-----------------------------------------------------------------
adywiki
-----------------------------------------------------------------
adywiki No mentors found in config, skipping migration.
-----------------------------------------------------------------
afwiki
-----------------------------------------------------------------
afwiki Nothing new to save, skipping

@Urbanecm_WMF is helping to figure out why.

In T409170#11406385, @Sgs wrote:

@Urbanecm_WMF is helping to figure out why.

The problem is described in T411104: mwscript-k8s makes it challenging to run LoggedUpdateMaintenance across all wikis, Daniel Kinzler uploaded fixes to Core and GrowthExperiments, which need to be reviewed.

@Sgs also noticed that on kaawiki, the script errors out with:

kaawiki [9360699038247e008416e081] [no req]   TypeError: array_key_exists(): Argument #2 ($array) must be of type array, null given

This is happening, because an administrator manually edited the list of mentors to add themselves, and they used a non-existing user ID. Fortunately, that wiki does not have mentorship enabled in CC. I went ahead and fixed the mentor list, and I filled T412187: Help kaa.wikipedia to enable mentorship to check on the wiki (as it seems they attempted to enable mentorship, but unsuccessfully).