Why do you ship this crap with MediaWiki if it doesn't work? This ticket is up from 2007 and the issue remains.

Yeah, already figured it out, thanks.

Ok... so the solution was rather simple. I simply had to drop the l10n_cache table completely as it was somehow corrupted (older translations had issues, whilst newer ones didn't) and run the update script, which recreates the table.

I'll also include the debug log for pages where recent revision is broken (replaced some content with "xxx" to anonymize it):

Truncating didn't help. That's a real shame, as we're running a rather large wiki project with years of translations. Tagalog (language) seems to be broken and some more popular languages like Brazilian Portuguese are getting recent revision errors after being edited, i.e. blank pages.

Hmm.. I'm not exactly sure what I'm supposed to do here. What would be the recommended steps of troubleshooting this or where would it be appropriate to ask this?

It's also worth noting that I had to apply the following patch when updating to 1.34 back in December:
git pull "https://gerrit.wikimedia.org/r/mediawiki/extensions/Translate" refs/changes/81/560081/2

Hello @Aklapper, I was using the 2019/07 version previously, now I've updated to 2020/01 and the issue persists.

Whatever's going on here, it's spamming my email. Might want to figure out a better way of doing what you're doing, just an advice.

Okay, truncating fixed it.

In T146591#3843312, @Reedy wrote:

In T146591#3843075, @Lyrixn wrote:

For whatever reason running update.php stalls on "Renaming index lc_lang_key into PRIMARY to table l10n_cache" and crashes the mysql server if not aborted.

Updating from 1.29.2 to 1.30.0

Is your table very big?

For whatever reason running update.php stalls on "Renaming index lc_lang_key into PRIMARY to table l10n_cache" and crashes the mysql server if not aborted.