Cannot upgrade plugin

I have Vissual Composer version 4.5 with no licence.
I wasn’t able to access several parts of my pages and decided to buy the licence key.
I downloaded the zipped filed.
I tried to deactivate existing plugin to install the new version 5.2.1. When clicking on deactivate I get a blank page. When I refresh the page the plugin is not deactivated.

This my commercial website. I desperately need to make some urgent changes. this is business critical.

Please come back with a solution.
Thanks for the support you will provide.
BR

How did you get the unlicensed version? If this was downloaded somewhere that it shouldn’t then it may well have contained some malicious code which may have caused damage to your site.

Beyond that there could be numerous possible issues with hosting PHP, theme and or WP version/compatibility, and so on.

It will not really be possible for anyone in the forums to advise on this and I’d suggest either asking the author, although if (as is most likely) the problem is with the theme then they may not be able to help. Alternatively it may be worth looking for a freelancer to help resolve it at www.studio.envato.com

I have the same problem.
Obviously, my developer just used someone’s random VC licence. I’ve now bought and downloaded a license but cannot see where I put the new license key. Can you please advise.
Thanks.