I've also had fun experiences where the "special characters" differ in the description than in the implementation in a few ways.
Once I had a password accepted with non-alpha numeric characters which were considered invalid as input on the login screen and so even though my password was correct it would not let me log in because it was validated with different logic after creation.
Another issue I've seen is that the password was required to have only a certain subset of non-alphanumeric characters, but it did not explain or validate this client side so I had a password for which all the boxes turned green, but was still invalid.
In both cases only trial and error worked to find a valid password.