SAP Note 22099 - "maximum number of connected terminals reached"

Symptom:

When a user tries to log on to the SAP System, an error message is issued:
"Maximum number of connected terminals reached"

Cause and prerequisites

The maximum number of connections per instance is determined by parameter rdisp/tm_max_no (default setting: 200). When this number is reached, no further logons are possible.

Solution
The parameter must be increased. This can be done without any problems because it requires only little more ressources. After restarting the instance the parameter becomes active.
Note:
If you do not log off properly (for example, switching off the PC without logging off), the connection is retained until it is exited because of a timeout (see note 27320). As a result, the number of open connections may be greater than the number of users logged on to the system.