Error 21 relates to your Netfile access code. It can be found just under the date on your Notice of Assessment. It changes every year.  Check that to ensure you have the correct access code.

I usually sign in with a sign in partner, my bank.

Now I am getting this message:

Sorry, this is not allowed (Error
403)

You have requested a Web page or resource that you aren't allowed to access. What next?

• Return to the  ;
• Return to the ; or
•  and we'll help you out.

That error is from CRA's end. Please try it at a later time. We also suggest clearing cookies and cache or try using a different browser. 

I cleared the cache and browsing history....first tried edge...then Chrome...then downloaded Firefox....at least 4 times each way...called CRA...they said the issue may be I need a capcha reader...downloded one of them....NOTHING works for access.  Using McAfee software....very frustrated.

@mcg866302 AFR is currently unavailable at this moment, but it will be restored. Our development team is working on it. We appreciate your patience!

I also have same problems...I get error code:

Error—ERR.221

  I tried clearing cookies and cache or try using a different browser, signing in via Bank

I am afraid if try login too many times CRC will lock me out

.

@FoxyPinch An outage for CRA Autofill was reported. Is it now functioning for you? 

I tried again but I still get same error message:

@FoxyPinch That error is from the CRA side and not from TurboTax.