How to investigate when a CVS server return "error" wihtout explanations ?

[John]

Hi,
using eclipse cvs client, i have an error running cvs update. The TCP stream 
(of ethereal) shows that the end of the stream is:

...
0
E cvs update: Updating my_module/a/b
Clear-sticky my_module/a/b/
CVSROOT/Emptydir/my_module/a/b/
Clear-sticky my_module/a/b/c/
CVSROOT/Emptydir/my_module/a/b/c/
Clear-static-directory my_module/a/b/c/
CVSROOT/Emptydir/my_module/a/b/c/
Template my_module/a/b/c/
CVSROOT/Emptydir/my_module/a/b/c/
0
E cvs update: Updating my_module/a/b/c
Clear-sticky my_module/a/b/c/
CVSROOT/Emptydir/my_module/a/b/c/
error

I can't find any cvs server log file (like CVS_CLIENT_LOG but for the server). 
Is there one ? Where it is ? How can it be activated ?

And wiwhout log file, what could be the reason ?

Thanks for any help.