The error ui-800-3 in the Netflix application on your PlayStation is usually caused by a need to agree to Sony's Terms of Service, typically encountered after a PlayStation system update. To resolve the error, you will need to first quit the Netflix application completely before manually signing into PlayStation Network.
Manually Sign In To PlayStation Network
Hold the PS button, located in the center of the controller, for 3 seconds.
Select Quit.
From the Playstation Main Menu, select PSN, then Sign In
The PSN icon is located in the second column from the right in the XMB.
Enter your Playstation Network sign-in ID (email address) and password.
The PSN sign-in prompt is a black screen with white writing and will ask for your Sign-In ID (Email Address) and gives you the option to "Sign In Automatically (Auto Sign-In)." Checking this box will usually eliminate the need to sign in to PlayStation Network each time you launch Netflix.
Select Sign In.
You may be prompted to agree to the Playstation Network Terms of Use before you are connected to PSN. If prompted, read and agree to the Terms of Use.
Once you have successfully connected to PSN, launch Netflix and attempt to stream again.