It's a JSON parsing error. I don't know if it's a known error, but it's not one I've seen chatter about on this list. I've gotten it too and haven't really looked into it. I suspect it is a bug in the Emacs JSON parsing function. but that I can only support that suspicion with hunches and slander.
Just to round out my "me too" report: I sometimes get that error on opening a thread from the search view. It seems to be intermittent in that a thread will open just fine and then I'll select it again and I'll get the error. But that observation might be faulty memory. Best regards, James -------------- next part -------------- A non-text attachment was scrubbed... Name: not available Type: application/pgp-signature Size: 489 bytes Desc: not available URL: <http://notmuchmail.org/pipermail/notmuch/attachments/20120430/b502b3e4/attachment.pgp>