threadtools.cpp (3785) : Assertion Failed: Failed to create thread (error 0xc)
CWorkThreadPool::StartWorkThread: Thread creation failed.
Exiting on SPEW_ABORT
I don’t know what happened 
running server system is debian7.5 amd64
Did you make sure to move the steamclient.so from linux64 to the directory where the binary is?
Linux: Copy linux64/steamclient.so into tu/Tower/Binaries/Linux
Is that the server directory on linux64/steamclient.so?
Or has it steamcmd directory?
And thank you