Write of lock failed and other errors since hosting company upgraded.

I recently upgraded my hosting package with my hosting company and they migrated a website to the new server. The Website itself is working fine, but the log-in page is giving errors and I am unable to log-in. Do you recognise these errors and could perhaps offer me some direction?

http://justupmystreet.com/admin_LogIn.php

I found a test file on your forum and uploaded that also which seems to have the same error:

http://justupmystreet.com/sessionTest.php

My best guess is that your session_save_path setting in your php.ini file is not pointing to a valid directory.

Thanks for the reply Ray - I really appreciate you taking the time.

You believe that they have set the path incorrectly in the options panel or that the driectory itself containing these elements is not created?

I have uploaded the test file to another website I have hosted - this is php 7.3 (the other site being php 5.6) and the error is different:
http://hollandcreative.co.uk/sessionTest.php

I've looked into the php options set up in my cPanel and it is as follows (for php 5.6)

include_path - .:/opt/alt/php56/usr/share/pear:/opt/alt/php56/usr/share/php
session.save_path - /opt/alt/php56/var/lib/php/session

I know all hosting companies have different directories, but does that look OK to you?

It looks ok, but the path still might not be valid or have bad permissions. Send this to your hosting company in a support ticket and they should be able to fix it for you. It is a server configuration issue, not an issue with your php code.