by Séverin Terrier.
Hi,
I think people having this style of issue should really provide much more details, such as which type of backup, for which course, manual or automated, by web or cli, with(out) logs, with(out) user datas...
And tell if it's always the same course (or not).
If it's one course, perhaps have a look at log table(s), to see the number of lines concerned.
You can also try to update MySQL values (connect_timeout, wait_timeout and interactive_timeout) to put (much) more !
Séverin