Hi @Phillips, Keith,
I'm glad to hear you solve the problem, if you have any issue about SharePoint, you are welcome to raise a ticket in this forum.
By the way, since the Microsoft Q&A community has a policy that "The question author cannot accept their own answer. They can only accept answers by others.". and according to the scenario introduced here: Answering your own questions on Microsoft Q&A, I would make a brief summary of this thread:
[sharepoint 2019 server remove an invalid field]
I'm migrating a SharePoint 2013 site to SharePoint 2019, using the 3-phase method. After migrating the site to SP 2016, I tried to open a list and received an error.
The issue has been solved. Thanks for Phillips's reply and finding, the solution is:
Discovered the problem: a third-party solution for a filtered lookup column is present in our SP 2013 system, but not in SP 2019. I found the developer's GitHub page, where he has an updated version for SP 2016. That same version also works in SP 2019.
Here's the link for anyone interested:
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