Dynamics AX - The AOS has reached its limit for user sessions or memory consumption

Common message when trying to connect to Dynamics AX

The AOS has reached its limit for user sessions or memory consumption

there are a few possible reasons this has occured

1. Max number of users in AX set to 1 or less than the desired. fix by logging into AX
In Basic -> Setup -> Server configuration , alter connections to desired amount

2. SQL Server is running in single user mode preventing multiple logins, if this is for a specific database right click database , options, permissions and select multi user mode.

3. Dynamics Aos is not running or running with incorrect permissions. First step check the event viewer on the server running the AOS

4. SQL server permissions are incorrect this will usually relate to the same user that is running the AOS not having permissions to use the sql database.

apart from the above , will need more information to prevent this error. goodluck to all