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.
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.