mu4e error : Database empty; try indexing some messages

Question

I recently setup mu4e. My Setup : emacs25, mu 0.9.18, macOS Sierra

I used mbsync to download my emails.

When I do M-x mu4e, I get error error in process sentinel: Database empty; try indexing some messages

But I have :)

I checked mu4e-maildir. It is correct (which is where mbsync has downloaded the messages.)

mu index (as well as mu index --maildir=~/Maildir just in case) also worked well.

I can use mu find <pattern> successfully.

But mu4e can't seem to find the DB

I think this is some configuration mismatch.

How do I troubleshoot this ?

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References :

• About 4 year old issue, without conclusive solution with exact same error : https://github.com/djcb/mu/issues/198 (Edit: I read http://comments.gmane.org/gmane.mail.mu.general/938 thread. I mentioned above, I am not using procmail. Using mbsync as mentioned above)
• I have asked this question first on reddit (Albeit it started in slightly different context where I couldn't even get mu4e to work. But now I'm past that. https://www.reddit.com/r/emacs/comments/5srva7/mu4e_0918_emailing_with_emacs_now_even_better/deyf717/

Answer 1

I came back to the setup after almost 3 months. I enabled mu4e in my .spacemacs and uncommented all the other settings related to mu4e, and what do you know? It works !!

Off course, I'm not saying this is magic.

But I have a hypothesis.

Some time ago, I had moved all the spacemacs setup into ~/spacemacs and I used to start the emacs as HOME=~/spacemacs emac &

I think this used to throw off a lot of software. I used to ran into "unexplained" behavior, where "normal" troubleshooting doesn't help.

So last week, I moved off that setup, and now my .spacemacs and .emacs.d etc all are in my actual HOME (i.e. ~) like everyone else.

I think this alone has solved several problems.

mu4e may be one of those.

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I now start emacs from the dashboard using the icon (macOS) - which earlier I couldn't do, since I didn't know how to set different HOME when launching from the dashboard. So I was forced to always use the term (I'm not complaining. Just sayin)