“Type Error occurred when creating object: Magento\Eav\Model\Entity\Attribute\Source\Config”

As noted by most, this seems to involve attributes that did not cleanly migrate / has migration data issues

In my case it was an customer address attribute called 'address_valid'

A sure fire way to debug this is to just debug with a breakpoint in PHPSTorm on MagentoEavModelEntityAttributeSource constructor

make a small temp edit to function definition

and step through until you hit the null one(s).

You can also go with a conditional (mine happen to the be first attribute calling that routine, so I had nothing to step through)

Look back in the trace log until you find the AbstratAttribute.php entry, and select.

Then check within the class data for the offending attribute data

I had this same issue. It turned out to be some extra entries (not columns or source model) in the "eav_customer_attribute" table. Once I removed these entries the page loaded and worked fine.

I also found that this issue caused the customers address to be saved as a new entry on every order.

Go to the table eav_attribute and search for attribute "mailchimp_store_view" and deleted this row after taking backup of your table. it will fix your problem. i was also facing same issue. it worked like a charm. give it a try.

I was experiencing the same issue when trying to edit customers accounts and after checking the 'eav_attribute table' using Idham Choudry's answer here, i checked the table against a working Magento (2.3.4) and found that MailChimp had an erroneous attribute which had migrated over from Magento 1.9 but is now no longer needed.

After taking a backup of the database I simply deleted the 'mailchimp_store_view' attribute from the eav_attribute table and I can now edit customers again.

Finally i re-installed Mailchimp and everything is now working perfectly again.

Hope this helps anyone with the same problem

Try to look at the customer eav attribute with select value for frontend_input column in eav_attribute table, make sure the source_model column value is not null or empty or it fills with correct class. You can set value for frontend_input column to int if you wanna work on the source_model later

After a long debug and review migrated database I found the reason

• During migration I found that some of custom attributes were not there in migrated DB ( I don't know, Why !).

• Another important point is we should check the options for the select type attributes( options had not been migrated in my case).

These 2 can be the possible reasons for the error.

Please run this three commands and check:

php bin/magento setup:upgrade
php bin/magento setup:di:compile
php bin/magento cache:flush