Created attachment 135067 [details]
Details of the failing "Setting up Account" page

SUMMARY
I'm trying to set up a new imap account in kmail for a GMail account. The account wizard offers to detect the proper settings and seems to do so successfully.

However when I click the "Next" button  on the "Secure your communication" page, I immediately get the error
"Failed to set up the account"

When starting kmail from the command line to get console output, I notice the following error printed in the terminal:
org.kde.pim.accountwizard: Did not find D-Bus method:  "setAuthentication"  available methods are:
org.kde.pim.accountwizard: "destroyed(QObject*)"
org.kde.pim.accountwizard: "destroyed()"
org.kde.pim.accountwizard: "objectNameChanged(QString)"
org.kde.pim.accountwizard: "deleteLater()"
org.kde.pim.accountwizard: "_q_reregisterTimers(void*)"
org.kde.pim.accountwizard: "_q_serviceOwnerChanged(QString,QString,QString)"
org.kde.pim.accountwizard: Impossible to convert argument :  QVariant(int, 9)


STEPS TO REPRODUCE
1. Open kmail
2. Choose settings "Add Account..."
3. Enter credentials for a gmail e-mail address (may be an issue with any imap account for which the server data is in the Mozilla database, I have only tested with a gmail account)
4. Enable "Find provider settings on the internet" if not enabled
5. Click next
6. Click "Add Account"
7. Click "Next" again

OBSERVED RESULT
After step 5. the assistant will properly show the discovered server addresses for the provided e-mail address.
After step 6. the console error messages as mentioned above are printed. The assistant will at this point be showing the "Secure your Communication" page and doesn't show any signs of failure, although the console suggests something went wrong already at this point.
After step 7. the "Setting up Account" page appears and it immediately states "Failed to set up account."

I'll attach a screenshot with the details on this page.

Note this is with kmail 5.15.2, which is no longer in the list above, but it's what is currently comes with an up to date  Fedora 32 system.

EXPECTED RESULT
Account gets configured successfully.


SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Fedora 32
(available in About System)
KDE Plasma Version: 5.18.5
KDE Frameworks Version: 5.75.0
Qt Version: 5.14.2
Kmail2 version: 5.15.2

ADDITIONAL INFORMATION