I need a solution
I have recently completed several Service Desk Upgrades to 7.5 SP1 and a common error continues to show up in each upgrade.
Error:
'ddlActionVariant' has a SelectedValue which is invalid because it does not exist in the list of items.
Parameter name: value
This error appears when you enter a process automation rule with an action for :send email" within any ruleset.
Basically, you edit the rule and as you attempt to modify the the action you get a screen:

Your are still able to create another action. You can configure it but unless you are familiar with the previous configuration for what template is used, will need to guess or refer to your notes.
Prior to upgrading the Service Desk, I made very detailed notes for all the configurations within Service Desk. This has minimized the amount of guesswork I would have encountered it I did not to this action prior to the upgrade.
For the most part the upgrade was an huge success. With these minor issues, I am just happy that the Service Desk upgraded with minimal effort and minimal post configuration.
If anyone encounters this issue and has any answers on how to better prepare or correct the issue after the upgrade, please feel free to share.
Thanks,
Oscar Castaneda
Sr. Solutions Architect
XCEND Group