Help.  I am also running into the same problem!

I have Turbotax Premier Desktop.  I am also CA resident and running into the same message where I can't efile my state return. 

I did have two 529-B forms for CA tax withheld (new for 2021) and eliminated those to see if it would work. I also had Schedule S to claim credit for out-of-state taxes paid -- I've had these in the past with no problems.

I've deleted all these (529-B and Schedule S) and TurboTax still has the same response - can't efile due to

"return has withholding from a source other than Forms W2, W2G, 1099R, 1099G, 1099INT, 1099DIV, 1099B, 1099MISC, 592B, and 593"