While installing the WordPress theme on a new server I found the following error.
This is not a single issue, following possible reason can be responsible, i am only talking about the error in new theme installing,
PHP environment setting error.
If you have a new server configured then the possible reason can be for this is PHP environment variable error,
like your post_max_size, is 2M (2 MB). your theme file size is 10MB then it shows this generic error.
so first upload a file in the root directory and check PHP info
Suppose in my i found post_max_size 2MB and other value in less amount,
so what you need to do
find the Loaded Configuration File in the phpinfo()
and change the following parameter
upload_max_filesize to 64M
post_max_size to 64M
max_execution_time to 300
max_input_time to 300
and restart the server hope this will work
Please if this is not working then your problem is different.