If you are installing your theme from the WordPress theme installer, but get a message that says Are you sure you want to do this?, most likely your web server is configured with low PHP settings that only allow a certain size ZIP file to be uploaded via WP admin.
Most hosting companies configure their servers to only have the maximum file upload size limit at 8-10 MB, some are less. The MagPlus theme ZIP is currently about 24 MB in size which is due to the included plugins and all the demo content. So if you get this error, your web server is rejecting the upload due to the overall size of the magplus.zip file. WordPress is unfortunately giving you a rather ambiguous message in response. This is not a theme issue or bug.
There two ways to solve this problem.
1) You can get your web host to increase your PHP limits so a larger zip file is allowed to be uploaded. They will know which limits to set if you explain the issue.
2) You can upload your theme via FTP. It is very easy and efficient.
Recommended PHP configuration limits are as follows:
- max_execution_time 60
- memory_limit 128M
- post_max_size 48M
- upload_max_filesize 48M
You can verify your PHP configuration limits by going to the MagPlus > System Status tab in the WordPress admin area. Or by installing a simple plugin called WordPress PHP Info