I have inherited a site which was created by someone else (who i cannot contact).
it has multiple plugins installed, and all are working fine.
BUT - if i try and install a new plugin - I get the message:
"The plugin does not have a valid header."
I have tried various plugins - and the same error with each.
Also, if I try installing the same plugins on another WordPress installation, it works fine.
I've tried installing via FTP as well as through the WordPress installer.
Also, the plugin is not in a suddirectory - which is a common solution when googling the problem.