I created a custom report type with custom object Job as primary object and joined with task object just because the report type name and label can't be changed with the default report type. However when I deployed to the environment with namespace I can't see the report but get "Obsolete Report" error but. I have no problem when I deploy to the environment without namespace. Has anyone meet this problem before?
I am not sure this is going to be the answer but finally I resolved "Obsolete Report" error. This only starts show up when I create a report with join formated with namespace. I can create a joined format report in the namespace environment, but once you download it to my local environment and deploy to the same environment it starts giving me the "Obsolete Report". I know the report is not updatable so I create the same report with different but the result is still the same. However, if I create managed packaged from the environment and deploy to different environment all the sudden my report starts working. But just in case someone run into issue and blocked by this you might want to try to create a package and deploy and it might work. I hope the salesforce fix this issue so developers don't get flustrated from this error.