I just switched my log level to FINEST and did some dumps.
Unfortunately I'm useless for interpreting them. If I had to guess,
things fall apart around ReportEngine.createGetParameterDefinitionTask.
If you're brave, I've posted them here:
http://jameskoch.googlepages.com/FAILED.log
http://jameskoch.googlepages.com/SUCCESS.log
These were created using the following Viewer URLs. The only difference
between the two is that in the failed scenario I use a UNC syntax when
referencing the rptdesign file. It's notable that BIRT can apparently
read the file in either case, since my column definitions and such come
through fine.
FAILED:
http://localhost:8080/birt-viewer/frameset?__report=//localhost/Reports/AccountList.rptdesign&gTenantID=C0DD523E4B11DD119132001AA0ACB44F&__document=//myserver/Reports/OUTPUT/AccountList.rptdocument&__title=Account+List
SUCCESS:
http://localhost:8080/birt-viewer/frameset?__report=c:/Reports/AccountList.rptdesign&gTenantID=C0DD523E4B11DD119132001AA0ACB44F&__document=//myserver/Reports/OUTPUT/AccountList.rptdocument&__title=Account+List