There's no error reporting at all even for wrong URLs. I mistakenly used a wrong URL (.com instead of .org) for my server to and was wondering why it doesn't sync.

Here's an example session:

<pre>
~ $ fossil clone test
                Bytes      Cards  Artifacts     Deltas
Send:             597         24          0          0
Received:           0          0          0          0
Total network traffic: 447 bytes sent, 463 bytes received
Rebuilding repository meta-data...
0 (0%)...
project-id: (null)
server-id:
admin-user: dmitry (password is "a666f9")

~ $ fossil open test

~ $ fossil sync
                Bytes      Cards  Artifacts     Deltas
Send:             137          2          0          0
Received:           0          2          0          0
Total network traffic: 303 bytes sent, 467 bytes received
</pre>