I try to investigate which mod could be the source of the problem, but it seem to be 'random', one time is agricraft, another time is chisel... One moment it works and then the other it does not work anymore.
What could be the problem ?

modlist.txt

Please take a look at this first. https://github.com/ForgeEssentials/ForgeEssentials#reporting-bugs
We can't help you unless you provide more useful information

The problem is that there is nothing in the logs, not related to FE. I can provide the last from the client (the issue seems to come from there)

latest.log