Problem with Luma theme after 1.9.2.0 upgrade

[byron_stuart]

I installed a fresh version of Magento 2.2.5 and then used the data migration tool to convert data from a 1.9.2.0 installation. Mostly it is working but I am having trouble with using Luma, because 1.9.2.0 was using a different theme (I don't remember what the theme was). I saw a suggested reason on a forum that the problem is because I removed the source code of the original theme, but the theme is still in the database. Where will I be able to find the old theme in the database to remove it, is it in core_config_data or somewhere else?

If I go to Content -> Configuration I can edit Global and Main Website but if I try and save changes in Main Website Store I get an error 'Something went wrong while saving this configuration: Incorrect theme identification key'.

I also can't send emails from the 'Contact Us' form, I get the following error:

main.CRITICAL: Incorrect theme identification key {"exception":"[object] (InvalidArgumentException(code: 0): Incorrect theme identification key at /home/mrsthtno/public_html/vendor/magento/framework/View/Design/Theme/FlyweightFactory.php:60)"} []

[Manish Mittal]

@byron_stuart

in the table 'core_config_data', it is needed to delete this record : 'design/theme/theme_id'.

delete from core_config_data where path = 'design/theme/theme_id';

var, app/etc and pub/static should be writable.

Refresh cache also. php bin/magento cache:flush

[byron_stuart]

Thanks for your suggestions, I just did all of them and it made no difference to either of the problems.

[Manish Mittal]

@byron_stuart

Please find theme entries in core_config_table and if there you find any unwanted remove it. Flush cache and try again.

[byron_stuart]

I solved my 'Contact Us' not sending email problem (see below). But now I get a different error when I try and save changes to template settings. When I go to Content -> Configuration -> 'Main Website Store' and try and save change I get this error 'Something went wrong while saving this configuration: Area is already set'. Previously I was getting 'Something went wrong while saving this configuration: Incorrect theme identification key', some progress I guess but I still can't save.

I had to delete some entries from core_config_data (but different ones to those that were suggested to me) and I had to change the core_config_data entry with path 'contact/email/email_template' to have a value of 'contact_email_email_template' previously in 1.9.2.0 the valid value had an 's' after the word contact, see this topic:

https://community.magento.com/t5/Magento-2-x-Programming/Magento-2-2-Contact-Us-page-can-t-send-emai...

[Manish Mittal · Accepted solution]

@byron_stuart

Please follow below workaround shared in link:

https://magento.stackexchange.com/questions/225628/something-went-wrong-while-saving-this-configurat...

[byron_stuart]

 @Manish Mittal Thanks for your help, can you please tell me one other thing?

When the solution says change in Magento\Email\Model\AbstractTemplate.php where exactly is that? The only place I can find that file is public_html\vendor\magento\module-email\Model\AbstractTemplate.php which is 'module-email' not 'Email'.

[byron_stuart]

@Manish Mittal I notice that this fix was necessary for 2.2.4, I'm using 2.2.5, shouldn't it have been fixed?

Another question in relation to paths. I found a solution for disabling account creation and the instructions said to make a file in \Plugin\Customer\Model\Registration\DisableRegistrationPlugin.php but I can't find any such folder path. There seems to be something understood about Magento paths that I am not getting.