I'm hitting this exact issue in August 2025 for a Federal with CA state. I tried every combination of tricks including efile just Fed, efile Fed and CA together, Check for Updates, reboot, uninstall plus reboot plus reinstall. None worked... I still get the FAILED_VALIDATION error code telling me that there is an update available even though Check for Updates tells me Your software is up to date.
I called Support and after 66 minutes of trying the full set of tricks the error is still occurring. My ticket is being escalated and I hope the next level support representative can resolve, otherwise I have to manually file both Fed and State.
