Password length

[Ruebo]

Is there a maximum length for a password?
I tested a few passwords of different lengths and it seems that the maximum working length is 50 characters. A password with 51 or more characters is accepted when changing passwords but when I try to log in afterwards it isn't accepted and neither is the original one. The long password is treated as if it would be the wrong password.
Is this just a problem on my side? If there is a maximum length, a notice when changing or first creating your password would be nice as e.g. my password manager uses a default of 64 characters. You can easily change the password if it isn't working but an indication beforehand would be helpful.