Error "could not connect to TSM Controller" When Logging in to Tableau Services Manager

Issue

When logging in to Tableau Services Manager (TSM), by running: TSM login –u <username> ; the following error may occur:

"Could not connect to TSM Controller at <hostname>:8850"

In windows customer encountered this when attempting to run any TSM commands after changing the Hostname.

Environment

Tableau Server on Linux
Tableau Server on Windows 2018.2. and newer

Resolution

Tableau Server on Linux:

Confirm port 8850 is not blocked by a firewall and the tabadmincontroller process is running on port 8850. For more information, see Configure local firewall in Tableau Help.
Confirm the hostname of the Tableau Server computer has not been changed since installation. For more information, see Installing Tableau Server in Tableau Help.

Tableau Server on Windows (TSM versions only):

Confirm port 8850 is not blocked by a firewall and the tabadmincontroller process is running on port 8850. For more information, see B efore you install... in Tableau Help.
Confirm the hostname of the Tableau Server computer has not been changed since installation. For more information, see Installing Tableau Server in Tableau Help.

Cause

The tabadmincontroller process - which handles TSM requests - is installed on port 8850 by default. Either the process is not running, or port 8850 has not been opened in the firewall, or the hostname of the Tableau Server computer has been changed after installation.