Error 25300 when opening return in TurboTax Premier 2021

[SweetieJean]

See if this helps:

What's error 25300? (intuit.com)

[timgrig]

I believe this has to do with the return.  I tried uninstalling TT and reinstalling and get the same error for this return.  It will not open the step-by-step so that I can file.  My daughter's return opens fine.  Is there anything I can do to get this return back so that I can file?  Maybe start a new and import in or something?  I really don't want to start over with this return.

[timgrig]

When trying to go to step-by-step it throws this error for this return.  But I was able to go to File / Electronic Filing / File Electronically and it opened the step-by-step.  Odd but now seems to be working so that I can file.

[lihlen]

I was able to correct Error 25300.  This error states that something in the return is forcing the return to open in Forms Mode and it won't allow you go back to Step by Step Mode.  We checked to see if a new return could be started in Step by Step Mode.  It worked fine, so I concluded there was a corruption in the .tax data file itself, not the software.  
First, we checked to make sure Turbotaxx was up to date.  Top menu dropdown Online, then Check for updates.  Make sure windows is also up to date. SOLUTION:  While stuck in Forms Mode, click the top menu File, go down to Electronic Filing, then File Electronically.  This cleared the error and allowed us to switch to and continue using Step by Step Mode.  Hope this helps!!