how to debug ssh connection issue, that report error "bin/bash No such file or directory"

[qiudaomao]

one of my remote machine (ubuntu 20.04) ssh connection will failure with waveterm.
When I click the connection button and select this server it prints below error message:

process finished with exit code = 1

bash: bin/bash: No such file or directory

process finished with exit code = -1

bash is there on remote machine

~/.waveterm/shell/bash which bash
/usr/local/bin/bash
~/.waveterm/shell/bash ls /bin/bash
bash     bashbug  
~/.waveterm/shell/bash ls /bin/bash
/bin/bas