The PyCdlib library can fail for a number of reasons. The most common reason for an unexpected failure is when an ISO file doesn't follow the relevant standards. In these cases, PyCdlib will usually throw a PyCdlibInvalidISO exception (though it can also throw a PyCdlibInternalError in some circumstances). If this happens, the absolute best thing to do is to open up a new issue, putting a pointer to the problematic ISO in the issue. If the ISO file cannot be shared, then a new issue should be created anyway, with the relevant backtrace from PyCdlib in it. From there, additional information can sometimes help to identify the root cause of the issue.