If your ,tax2019 File has any state returns in it you need to first download the state program.

After you get the program installed the first thing to do before you open your tax return is to update the program and install any state programs you had. Then open your file. So you first might need to start a fake return to be able to download the state program (go to FILE - NEW TAX RETURN)

Then go to FILE -Open and find your return.

See error 190

https://ttlc.intuit.com/community/bugs-and-error-messages/help/error-190-when-opening-file-in-turbot...

Problem Solved, Thank you.  JC

I prepared my return in 2018 with TurboTax including my Idaho return.  I tried to open my copy of the file after doing an update, since it has been ages since I used TurboTax 2018.  After the software update and I clicked to open my return, it said I needed to download the state (error 190), it says

"Hmm...it looks like we've hit a slight snag"
Try Again?

This is a loop.  How do I get into look at my Federal return?

After you get the program installed the first thing to do before you open your tax return is to update the program and install any state programs you had. Then open your file. So you first might need to start a fake return to be able to download the state program (go to File-New Tax Return).

Then go to FILE -Open and find your return.

But you may not be able to update 2018 or download the state program now.  You might need to get a copy from the IRS.   OR you could try the TaxPrinter service to convert a .tax file to pdf at

http://www.taxprinter.com

They might be expensive and it is probably not safe to email tax returns back and forth.  They are not related to Turbo Tax.