When trying to upgrade from 1.31 to 1.34 update.php is failing with the following information
Migrating revision data to the MCR 'slot' and 'content' tables, printing progress markers.
For large databases, you may want to hit Ctrl-C and do this manually with
maintenance/populateContentTables.php.
Populating revision...
... revision processed up to revision id 500 of 79590 (383 rows in 0.17646288871765 seconds)
...
... revision processed up to revision id 27500 of 79590 (25540 rows in 6.0020930767059 seconds)
Failed to populate content table revision row batch starting at 27501 due to exception: MediaWiki\Storage\BlobAccessException: Unable to fetch blob at tt:27622 in /home/public_html/live/public/includes/Storage/SqlBlobStore.php:295
Stack trace:
#0 /home/public_html/live/public/maintenance/populateContentTables.php(385): MediaWiki\Storage\SqlBlobStore->getBlob('tt:27622')
#1 /home/public_html/live/public/maintenance/populateContentTables.php(287): PopulateContentTables->fillMissingFields(Object(stdClass), 'wikitext', 'tt:27622')
#2 /home/public_html/live/public/maintenance/populateContentTables.php(241): PopulateContentTables->populateContentTablesForRowBatch(Object(Wikimedia\Rdbms\ResultWrapper), 27501, 'revision')
#3 /home/public_html/live/public/maintenance/populateContentTables.php(108): PopulateContentTables->populateTable('revision')
#4 /home/public_html/live/public/includes/installer/DatabaseUpdater.php(1394): PopulateContentTables->execute()
#5 /home/public_html/live/public/includes/installer/DatabaseUpdater.php(490): DatabaseUpdater->populateContentTables()
#6 /home/public_html/live/public/includes/installer/DatabaseUpdater.php(454): DatabaseUpdater->runUpdates(Array, false)
#7 /home/public_html/live/public/maintenance/update.php(205): DatabaseUpdater->doUpdates(Array)
#8 /home/public_html/live/public/maintenance/doMaintenance.php(99): UpdateMediaWiki->execute()
#9 /home/public_html/live/public/maintenance/update.php(277): require_once('/home/public_ht...')
#10 /home/public_html/live/public/update_domain.php(12): include('/home/public_ht...')
#11 {main}
As far as I can tell, this is the revision it's having a problem with: https://bahaipedia.org/index.php?oldid=27622
I am not sure how to go about troubleshooting this issue. I did try and run populateContentTables.php separately but got the same error. As an experiment I switched to the master branch but the update still failed.