Separate the account from the application update
A television may still display TV3 while the current service is called 3Cat. The official help gives model-specific guidance for an available update and alternatives when the television cannot update. That is a software-compatibility question, not proof that the old account is invalid.
Read the television model and open its actual app store. Note whether it offers 3Cat, an update to TV3 or no compatible app. These results determine the next device step more clearly than registering another email address.
Try the established credentials on the official service
Use the normal 3Cat sign-in route and the email associated with TV3 or Catalunya Ràdio. If the password is forgotten, use official recovery for that account rather than create an unrelated identity just to make a login screen disappear.
Keep recovery emails and sign-in links private. If a television shows a pairing prompt, follow the current official flow from your own phone or computer. A stranger does not need your account password to explain compatibility.
Check the platform if browser sign-in works
A working website login and a failed television app help narrow the issue. Check the television’s supported platform, app version and actual store availability.3Cat’s help names specific TV generations and certified AndroidTV requirements.
If the built-in app is too old, inspect the published external-device alternatives. Changing account identity cannot update the operating system or turn an unsupported app into a current distribution.
Then investigate the programme you want
Successful sign-in does not grant every programme worldwide.3Cat’s overseas help describes title-level restrictions, while much of the catalogue is offered internationally. If only one film or series is restricted, record its title and your viewing country before changing the account again.
For support, provide the old account service, whether website sign-in succeeds, television model and exact message. Avoid including a password. This keeps the account-migration question separate from device support and programme rights, allowing the next action to address the actual cause.
Questions about this guide
Must an existing TV3 user register again?
No. The official help says existing TV3 or Catalunya Ràdio credentials can be reused.
Can a new account fix an unsupported television app?
No. Account creation does not change the television’s software compatibility.