Thread:Project:Support desk/Upgrade from 1.15.2 to 1.23.0 with section errors/reply (13)

This error may happen if the latest revision for that page doesn't contain the corresponding text from the text table. If that's true, the problem would be the database and not the PHP version you use.

That's apparently the cause, since the example page you gave, has a revision history, and the latests revisions can't be accessed, but older ones are still intact.

Apparently, all revisions since oldid=1490 (30th january 2014) are lost.

If you restore your database to the state prior to the upgrade, does the wiki work? Are those pages accessible?