Can't install plugins and registration error


I can’t install plugins in my site,error message says it couldn’t copy files ect,don’t know what to do.
-And again my user registrations has a problem,its impossible to register, it says "cannot read property success of null"and sometimes say ‘nonce error,please reload’…will this problem stop if I change the user registration plugin and install a different one? please assist.

The first problem can be solved by downloading the plugins locally from’s plugin directory, then uploading them in the Wordpress admin panel.

The second issue may be related to the registration plugin you’re using - try a different one and see if you get the same issue.

Thanks a lot,its now working