Connection Limit Reached on Print Server or License Server


There is a defined connection limit in ScrewDrivers Print Server Agent v6 and Tricerat License Server v2. The setting defines a limit for active concurrent connections to the server. When the limit is reached, no new connections will be established with the server, resulting in failed license checks, failed printer queries, or failed print jobs. The default limit of 256 is in place to prevent the server from becoming unstable due to excessive resource usage.

If logging is turned on for the license server or print server, the following line will appear in the log file:

Log File
FAIL: Connection limit of 256 reached on port 3550. Connection refused.


If the connection limit is reached during normal production operation, the limit can be safely increased. This is sometimes necessary in large environments.

  1. Run regedit.exe
  2. Open the key HKEY_LOCAL_MACHINE\SOFTWARE\triCerat\Simplify Licensing or HKEY_LOCAL_MACHINE\SOFTWARE\Tricerat\Simplify Printing\ScrewDrivers Print Server v6
  3. Add a new REG_DWORD value named ConnectionLimit.
  4. Set the value data to the max simultaneous connections. The default value is 256. Setting this value to 0 will disable the limit, allowing unlimited connections.

    Tricerat Recommendation

    If 256 is insufficient, Tricerat recommends increasing the value to 512 or 1024. Disabling the limit is generally safe but removes any protection of connection counts consuming the system.

  5. You must re-start the service before the new setting takes effect.

Additional Information

For a print server, a connection occurs during a user login and during a print job. During logon, a connection is made to the print server to query information about the necessary printers. During a print job, a connection is opened that sends print data to the print server. Additionally, a user opening the Advanced Print Features dialog will trigger a connection to the print server.

All connections are non-persistent, meaning that they will close as soon as the operation is finished. During login, the connection will likely only be open for a few seconds. During a print job, the connection is likely to complete within a few seconds but it can go longer depending on the size of the print job. Since these are non-persistent connections, the concern for the connection limit is simultaneous connections within a window of a few seconds.

Generally, this setting is only a concern in large environments with heavy print traffic. Only change this setting if there is behavior described in the "problem" section or under advisement from Tricerat Support.