[xlii]

I had a very similar issue some time back that was caused by LSP.

Long story short I had multiple long running LSPs (fragmented projects) in Emacs that would open many handlers and keep them open. At some point same error started happening and I thought only restart could resolve it.

But then I was at the hotel where merely switching network made this issue to appear (I suppose binding was somewhat related to and switch made pool exhaust pool quicker) so I decided to debug it.

It turned out that restarting Emacs was enough to close file handlers and resume operations.