Did you run the migration tool? These are all stored in the DDS which has strongly type references in the database to classes, I've seen in some other areas classes move in CMS 12 and the migration tool updates these in the DDS
Do you mean the upgrade assitant or the DXP project migration? I've run both. And submissions are stored just fine, just can't export them. So most of the DDS should be fine at least?
I guess next step is to get Foundation up and check if it's working there.
Update: it does work in Foundation of course, so as usual its my fault :/
This was actually due to new JSON conventions in dotnet core i think. At least Forms worked fine after we removed Newtonsoft and UseMemberCasing() from Startup
services.AddControllersWithViews() .AddNewtonsoftJson(o => o.UseMemberCasing());
Then we needed to more explicitly tell the JsonSerializer to use PascalCase a few places in our code and we were good
After upgrading to cms 12, its no longer possible for us to export form submissions. The export options are all 'undefined', and if clicked all of them makes a txt file that will fail to download.
Any ideas what could be wrong? We have very little custom config for forms except some custom elements.