When installing a new theme in appearance > themes > add new, the following message can sometimes be displayed :
This message is displayed because your server settings for upload max size or maximum memory are not well configured.
Don’t worry, this is a common issue, very simple to fix.
If you are not used to set your server php / memory settings, contact your hosting company to do it for you. This is their job, it takes 1 minute to do.
Show them a screenshot of your error, or email them the error message. Ask them to assist by increasing the following values, until you are able to install your theme or upload your image.
memory_limit upload_max_size post_max_size upload_max_filesize max_execution_time max_input_time