Making sense of failed book

I added a new book to my Booklore library last night, but have not been able to open it to read it or send it to my Kobo via OPDS. I'm getting two errors in my logs, one in the Booklore logs, one in the Booklore-DB logs:

Booklore Log

2025-11-04T19:43:21.502-05:00 ERROR 10 --- [booklore-api] [nio-8080-exec-9] o.s.w.s.s.s.DefaultHandshakeHandler : "Handshake failed due to invalid Upgrade header: null"

Booklore DB Log

fsdfd2025-11-04 17:26:14 1400 [Warning] Aborted connection 1400 to db: 'booklore' user: 'bookloreuser' host: '172.25.0.2' (Got an error reading communication packets) 

I'm running Booklore on the NVME storage pool on a Synology 923+. Any advice for a relative n00b on how to track down the source of the problem and fix it?