cannot load elfeed, message elfeed-db-load: Hash table data is not a list

[brabalan]

I just updated elfeed to 4.2.1 (commit acbb86e) and I no longer can launch elfeed (I get the message elfeed-db-load: Hash table data is not a list and the window just says Database not loaded.).

The beginning of the index seems wrong:

❯ head -n 6 ~/.elfeed/index
;;; Elfeed Database Index (version 4)

(:version 4 :feeds #s(hash-table test equal data -no
e-l6 (mode-line-elt-no 1)))
1)))
 of Code 2024 in pure SQL" "http://databasearchitects.blogspot.com/2024/12/advent-of-code-2024-in-pure-sql.html" 1735845650.0 #s(elfeed-ref "4625c4951ee51328b1d71921db1ce000b7885d4b") html nil nil "https://hnrss.org/frontpage?points=100" (:authors ((:name "greghn")))) ("feeds.arstechnica.com" . "https://arstechnica.com/culture/2025/01/its-january-which-means-another-batch-of-copyrighted-work-is-now-public-domain/") #s(elfeed-entry ("feeds.arstechnica.com" . "https://arstechnica.com/culture/2025/01/its-january-which-means-another-batch-of-copyrighted-work-is-now-public-domain/") "It’s January, which means another batch of copyrighted work is now public domain" "https://arstechnica.com/culture/2025/01/its-january-which-means-another-batch-of-copyrighted-work-is-now-public-domain/" 1735845182.0 #s(elfeed-ref "67ec8258777115c2e3a644e34a0162774c9a0ea3") html nil nil "http://feeds.arstechnica.com/arstechnica/index" (:authors ((:name "Andrew Cunningham

Is this corrupted? Is there some way to get the index back?

(By the way, the variable elfeed-version reports 4.0.1: https://github.com/emacs-elfeed/elfeed/blob/main/elfeed.el#L53)

[brabalan]

As a follow up, I replaced the whole .elfeed directory (index and data) with a backup from a couple days ago. The start of the file looks much saner and I was able to load elfeed. I will update this if I see some further corruption.

[minad]

Which Elfeed version did you use before? There have been no database changes in recent Elfeed versions. It seems your file got corrupted, as if some part of the file is missing. Maybe it was edited accidentally? Maybe you used some syncing method which broke it (#665)?

[brabalan]

I have not yet set up any synchronization, and I'm regularly updating elfeed from the git. I did some experiments and it seems the database is not saved if the elfeed-search buffer is not quit (I let my emacs idle for a long time, nothing happened, and quitting the elfeed-search buffer wrote the index within a few seconds). So I suspect that at some point I quit emacs with elfeed-search still there, and it did not have time to fully write the index file.

[minad]

So I suspect that at some point I quit emacs with elfeed-search still there, and it did not have time to fully write the index file.

Elfeed writes the database atomically so such corruption should not happen.