[Evolution-users] Constantly have to clear cache

[Milan Crha]

On Sat, 2025-11-08 at 02:00 +0100, Steve Phillips wrote:
> Unable to retrieve message.Empty cache file:

	Hi,
that error used to happen quite often some years ago, like very very
very often. It can still happen, but the code does not bother the user
when it does in some known cases. If I recall correctly, one way to
reproduce it is when the message is moved elsewhere while other part of
the code has scheduled to work with it. Imagine you've set the Inbox
for offline use, it means every new message is automatically downloaded
to the local machine. Then you have a filter, which moves some of the
messages into their own folder. The offline download schedules download
of the new messages and processes one message after another. Before it
gets to the message, the message is moved elsewhere by the filter, to a
different folder. When the offline download gets to the message, the
server returns not data and "OK" response (no idea why they do it, when
the message is not there, but it's what I received on some servers at
least). As no data was received from the server the cache file is left
empty, and when it's tried to be used, to convert the file to a MIME
message, it's realized the cache file is empty and the error is passed
to the callers. That's only one way to reproduce I recall from those
days.

The error itself means that something failed while downloading a
message, even the server did not return any error code. It's not
necessarily the message is gone from the server, it can be the local
cache state does not match the server state, or a problem with the
cache directory permissions (one reason to write the whole path to the
empty cache file in the error message), or, well, anything else.

When/if you get the error again the next time, try to select a
different message and then back the faulty one. It can re-download the
message. If it'll not help, then refresh the folder, which will
synchronize the local cache with the server content. An interesting
observation would be whether the offending message disappeared or
whether it could be loaded fine after the refresh. It's possible the
message changed its UID on the server, though I guess it unlikely, it
should not happen that often as it does for you.

	Bye,
	Milan