PHP Errors - possible firewall block?

Question

On the site, the errors shown below are appearing on the bottom of the home page, and also appear when I try and complete a SagePay test payment.

Doing a bit of digging, it appears it may be something to do with a firewall blocking permission, but not sure. Can anyone confirm this, and also, does Expression Engine need to connect to a port?

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A PHP Error was encountered

Severity: Warning

Message: Unknown: open(/var/lib/php/session/sess_4l2sqvju8b8ji8usse9vq4ekk7, O_RDWR) failed: Permission denied (13)

Filename: Unknown

Line Number: 0

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A PHP Error was encountered

Severity: Warning

Message: Unknown: Failed to write session data (files). Please verify that the current setting of session.save_path is correct (/var/lib/php/session)

Filename: Unknown

Line Number: 0

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Answer 1

It seems it can't write to the folder because of incorrect permissions on the folder.

Possibly change the location of where the sessions files are saved (e.g. in a tmp_sessions folder) and change the location in Plesk.

Answer 2

given you're using CartThrob and SagePay - we had a similar problem back in December. Have a look at extload.php inside themes/third_party/cartthrob/lib and update as required.

That certainly fixed our issue.