Hi @TRex2022 !

Are you using a local vault or a 1Password membership?
If you are using a local vault, the Master Password should be the password that belongs to the vault and which you are using to unlock this vault.
If you're on a membership, you should be able to log into your account on https://my.1password.com, https://my.1password.eu or https://my.1password.ca. The password you are using to log into your vault here is your Master Password.

Maybe this article could also help if you are not sure about your Master Password.
https://support.1password.com/forgot-account-password/

Hi DenalB,
thanks for your reply.
Well I have a membership and everything works well on my laptop. But not on the Iphone :-(
Up to now I think I tried evrything without having success. Laptop ok 👍 Iphone not okay 👎 !!!
Shall I reinstall the 1pw app on the cellphone?
Any other suggestions?

Thanks for your support!! 🙏💫
Thorsten

Which PW is ment by masterpassword (MPW)? MPW of App? Or MPW of 1PW?

Do you have a Primary vault present on the mobile device? It sounds like it there should only be one password and that is the one you use to access the membership.