User login and get a blank page

[LazyMan]

User type in username and password, click login and receive a blank page.
my version Joomla 3.9.11 Virtuemart 3.4.2     megadeal template
Any help will be much appreciated.

[Jörgen]

Probably template issue.
Please test with protostar template.
Jörgen @ Kreativ Fotografi

[jenkinhill]

A blank page usually indicates a 500 error. If it works OK with Protostar then this may help identify a template issue:  http://forum.virtuemart.net/index.php?topic=117042.0