Many issues you may run into such as: white screen, demo content fails when importing, empty page content, changing skin problems and other similar issues are all related to low PHP configuration limits. The solution is to increase the PHP limits. You can do this on your own, or contact your web host and ask them to increase those limits to a minimum as follows:
max_execution_time: 240 or greater
memory_limit: 320M or greater
post_max_size: 64M or greater
upload_max_filesize: 64M or greater
max_input_time: 120 or greater
Also consider upgrading your PHP version to the latest version, the newer the better.
How To Verify Your Current PHP Limits?
You can verify your PHP configuration limits by installing a simple plugin Host PHP Info by Arefly.
Updating your PHP version
In most cases you cannot update the PHP version yourself and need to contact your host about this. The upgrade process is an easy process and should be something your host can do for you without impacting your website or charging you a fee. Here’s a letter you can send to your hosting company: