It looks like if you use -scancms option, it will fail. You can remove that option, since it is optional.
symptom
When running Reposcan in BI 4.0 and using '-scancms' with either True or False, the result will return the following error "Initializing...Internal error: An unknown exception has occurred"
Cause
The issue was raised as a product defect in BI 4.0
Resolution
The issue was raised as a product defect and will be tracked in ADAPT01702230, which has a milestone for SP08