Notice: unserialize(): Error at offset 0 of 12025 bytes etc..

I have tried to update opencart 1.5.6.4 to 2.0.3.1, but now I cannot login to admin page. I got errors
Notice: unserialize(): Error at offset 0 of 12025 bytes in /home/xxx/public_html/system/library/user.php on line 47
Warning: Cannot modify header information - headers already sent by (output started at /home/xxx/public_html/admin/index.php:80) in /home/xxx/public_html/system/library/response.php on line 12.

I have tried look for a solution, but have not been able to find any.

Now I have following errors too:

Could not load language ! in /home/xxx/public_html/vqmod/vqcache/vq2-system_library_language.php on line 39. I have 3 language in my shop (english, finnish and swedish). All the language files are in admin and catalog and there are no extra xml files in qvmod. Code of the vq2-system_library_language.php on line 39 is
Cannot modify header information - headers already sent by (output started at /home/xxxx/public_html/admin/index.php:85) in /home/u37731/public_html/system/library/currency.php on line 45

You have tried to clear VQMod cache?

That's an error from the 1.5.x file not 2.x. Try clearing your vQmod cache and disabling all your vQmods.

I cleared vQmod cache and disabled all vQmods and still have errors: unserialize(): Error at offset 0 of 12025 bytes in system/library/user.php on line 49
Warning: Cannot modify header information - headers already sent by (output started at /admin/index.php:80) in /system/library/response.php on line 12

There is probably an issue with the permission value in user_group database table. Try checking it with the default from the install SQL.

https://github.com/opencart/opencart/bl ... .sql#L3348

Thank you for help, but unfortunately it did not have any effect. I am beginner with phpadmin so I want to make sure that permission value can be modified here:

Use the SQL command to insert...and not edit and Copy/Paste.

I was able to log in admin and unserialize(): Error diappeared. I was able to set permissions for user groups. Suddenly I got error: "Service Unavailable
The server is temporarily unable to service your request due to maintenance downtime or capacity problems. Please try again later." and cannot log in anymore.

Error_log:
Trying to access array offset on value of type null in /public_html/index.php on line 173
PHP Warning: Undefined array key "en" in /public_html/index.php on line 174
PHP Warning: Trying to access array offset on value of type null in /public_html/index.php on line 174
PHP Warning: Undefined array key "en" in /public_html/index.php on line 177
PHP Warning: Trying to access array offset on value of type null in /public_html/index.php on line 177
PHP Warning: Undefined array key "en" in/public_html/index.php on line 178
PHP Warning: Trying to access array offset on value of type null in /public_html/index.php on line 178
PHP Warning: Cannot modify header information - headers already sent by (output started at/public_html/index.php:98) in /public_html/system/library/currency.php on line 45

Check your server error logs or contact your host.

ADD Creative wrote: ↑

Sat Jan 08, 2022 9:38 pm

Check your server error logs or contact your host.

Or she/he can relax and give me some beers for upgrade