Symptoms
You might get this runtime error when exporting the site with Prime Mover using PHP 8.0+
Causes
Some third party code (not yet fully identifiable) alter the way cookies are being handled – instead of a string – the cookies become an array type. The tricky thing is that this is not consistently reproducible – even though the test site uses the same plugins/themes and PHP version (8.0). The issue is no longer reproducible.
This will cause fatal error only when you are using PHP 8.0+
Solution
The only working solution for this issue is to downgrade PHP of the source site to PHP 7.4. Once downgraded – confirm that you are really using PHP 7.4.
Once confirmed that the PHP version is now downgraded to PHP 7.4 – repeat the export process. There should be no more runtime errors.
Once the export is completed – you can switch back again to PHP 8.0+.
Help us fix this error
If you are able to reproduce this error on a test site where we can access (not a production site) – then that would be awesome. Please send us a ticket here with the login access to your test site where we can reproduce this issue.
This would greatly help in finally closing this issue. Thank you!