[Error Message] Unable to Change Usergroup from ACP

[JunJoo]

I am unable to change the usergroup of member from ACP.
When I change a member usergroup from mod or sumo to registered or any other who have no power.

Like I changed a member awaiting member's group to registered from ACP it returns an error message saying

The following errors were encountered:

• The style you selected is invalid. Please select a valid style.
  

 
I didn't changed any property. just display and primary user group.But when I changed its user group to Super Moderator (SuMo) it accepts it and usergroup is changed. Same as I tried a member's usergroup from registered to moderator. It accepts that but reverse is not possible giving me same error.
I tried hard refresh
deleted cookies and cache....
But still unable to find a solution.
Any help is appreciated.
Thanks

[Donald_Duck]

Maybe ACP Theme issue, what theme you're using! Did you test with stock theme !

[JunJoo]

Its default ACP theme...

[Ben]

Switch to the account settings tab while editing the member in the ACP and scroll down to theme and ensure it is the one you are using on your board.

[JunJoo]

The theme in accounting setting is the one I am using on my board. I set it as a default board theme and it is the one in user profile.

I tried another theme (its color variant) other than default and it accepts the changes...

I wonder why its not taking the default theme I set for the board. Rather it accept another public theme.

Why So???


BTW Thanks Ben

[Donald_Duck]

Something broken with stock theme if custom theme work's. Check template updates in ACP to find the code changes done by some 3rd party plugin etc