I've just encountered an odd problem whereby the nodelets stopped part-way through. Looking at https://www.perlmonks.org/?node_id=11122359 the Nodelets only included the XP nodelet and the first half of the Approval Nodelet - it stopped just after the "moderation history" link. The rest of the nodelets were absent as was the page footer ("PerlMonks lovingly hand-crafted by Tim Vroom.", etc.). I had not been logged out, according to the rest of the page. To see if it was reproducible I opened the same page in a fresh tab and the nodelets all appeared as they usually do and the footer had returned.
Both requests would have probably been made at 13:27 BST (UTC +1) or so today.
I've never seen this before but it might, if related, shed more light on the intermittent 500s. HTH, either way.