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 Dendrite theme ZIP is currently about 15 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 dendrite.zip file. WordPress is unfortunately giving you a rather ambiguous message in response. This is not a theme issue or bug.
Memory Size: memory_limit = 256M Script execution time: max_execution_time = 400 Number of input variables: max_input_vars = 4000
If you don’t have access to the php.ini file, you can add the following values in your .htaccess file:
php_value max_execution_time 400 php_value memory_limit 256M php_value upload_max_filesize 10M
Be careful using these settings, some hosting companies don’t allow users to change php settings, if you experience any problem after making these changes, please revert these in your .htaccess file, using your FTP client.
Also there is another way to prevent this error, you can upload your theme via FTP.