Edit the /etc/imscp/imscp.conf file and set the DEBUG parameter value to 1.

Execute the installer with the –debug command line option.

The logs in both cases should be in the folder /var/log/imscp/, since there are several modules, you will have to check various files. Most of the information on failed upgrades/installs would be in those files.

/var/log/imscp/imscp-setup.log
/var/log/imscp/imscp-rqst-mngr.log