WordPress Migrator "Out of memory (tried to allocate bytes)"
This message means that the allowed PHP memory limit set on your host via the PHP memory_limit variable has been reached during the transfer process.
To resolve this problem increase the value of the memory_limit variable to a higher number and restart the migration process. SiteGround Cloud hosting customers can follow the instructions in this article to increase the variable.
Changing the value of the memory_limit variable is not usually allowed on shared hosting environments. If your website is hosted on a shared plan then you should check for and remove any unnecessary large files in the wp-content/themes and wp-content/plugins folders of your WordPress. Deleting unnecessary large files from these folders will decrease the memory usage of the plugin and resolve the problem. SiteGround customers can use the Site Tools -> File Manager tool to look for such files and remove them.