I encountered the following error while running oracle BI Publisher under tomcat:
getOutputStream() has already been called for this response
This error occurs when you have a user with roles assigned other than administrator and that user tries to access the shared folder.
Anyways got around to fixing it so I thought I'd mention it just in case anyone else encouters the same issue. I guess it is due to a bug in the security error redirector code.
Resolution: You need to share at least one folder to the user.
Stepwise guide :) :
Create new folder in the shared folders directory.
name it whatever you like.
Now go to admin interface and goto Roles and permissions. Create a new role.
Add datasources and any of the preconfigured roles to the newly created role.
Click on Add Folders and add the newly created folder:
Next assign the role to your user :). All set !