update cause issues with mutiplayer

[acidsaves]

update cause issues with mutiplayer , My friend updated his Panzercorp it was successful . Now when going multiplayer it says serial number is registered , I help him update panzer corp before this issue never happened before . . Can you help us fix this issue.

[VPaulus]

Welcome
The problem is not caused by the update, as the update don't change the login details nor the serial numbers.
Your friend will have to send an email to support[at]slitherine.co.uk stating the issue. He will have to provide in the email his Panzer Corps order details and account details, for us to check the serial numbers versus those registered in his account.