Hi there,
Thanks for replying to me!
The server php version is PHP 5.4.45-0+deb7u2, but our clients site has this message on the sync tab: 
So the sync has been running for 6 days without result…
Any idea where I need to look to solve this? We can’t just upgrade our server there are a wide variety of sites running on it, some don’t cope with newer php…The client never used to have any problems with the sync before…
Thanks again,
Marijke