Error "500 Internal Server Error" or "No Valid Session Found" Running tabcmd From Multiple Command Prompt Windows
Published: 26 Aug 2015 Last Modified Date: 31 Dec 2020
When you try to run tabcmd from a new command prompt window on a computer where tabcmd is already running in an existing window, the command fails and one of the following errors might occur:
500 Internal Server Error
No valid session found (errorcode=46)
Use one of the following workarounds:
Wait for the first script to finish, then run your next command in the same window.
Run tabcmd on a different computer.
It is not currently possible to run multiple instances of tabcmd from a single computer.
When more than one tabcmd session is running at a time, tabcmd logs will show something similar to the following:
 DEBUG 2018-06-07 18:46:21,818: ====>> Starting Tabcmd 9.2 at Thu Jun 07 18:46:21 CDT 2018 <<====  DEBUG 2018-06-07 18:46:22,917: ====>> Starting Tabcmd 9.2 at Thu Jun 07 18:46:22 CDT 2018 <<====  DEBUG 2018-06-07 18:46:22,935: ====>> Starting Tabcmd 9.2 at Thu Jun 07 18:46:22 CDT 2018 <<==== and then:  ERROR 2018-06-07 18:53:37,193: 500 Internal Server Error  ERROR 2018-06-07 18:53:37,242: 500 Internal Server Error  ERROR 2018-06-07 18:56:03,677: 500 Internal Server Error
In the above example, 3 different tabcmd sessions were started at the same time, and all 3 failed with the same error. The same issue will occur if sessions overlap. The first tabcmd session needs to finish completely before the second one can be run.
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