PHP error: "Database update failed - quitting!"

[Daniel-Mietchen]

After hitting the Link selected works to author button on https://author-disambiguator.toolforge.org/names_oauth.php?doit=Look+for+author&name=Arne%20B.R.%20Witt, I got (and am still getting) this error:

 session_write_close(): Failed to write session data using user defined save handler. (session.save_path: /var/lib/php/sessions) in /data/project/author-disambiguator/public_html/lib/wikidata_oauth.php on line 111

When it first occurred (see first screenshot), it also said

Database update failed - quitting!

The issue is affecting multiple Author Disambiguator pages (perhaps all) - see this other example:

While poking around, I got an additional mysqli::query(): (08S01/1053): Server shutdown in progress in /data/project/author-disambiguator/public_html/lib/batch.php on line 170 Database error: Server shutdown in progress on https://author-disambiguator.toolforge.org/batches_oauth.php, which may give a hint to what is going on (i.e. some server shutdown).

Things worked fine for me until about an hour ago - here is my last edit using the tool before the errors popped up.

[Daniel-Mietchen]

Things are back to normal - here is the first Author Disambiguator edit I made after opening this ticket.

Seems the server was indeed restarted. Closing.