This Bugzilla instance is a read-only archive of historic NetBeans bug reports. To report a bug in NetBeans please follow the project's instructions for reporting issues.
Create/open a web project. Create some directory in your home. Try to add this directory to the project sources. (Add Folder action on Sources node in project customizer). The message appears saying that source root is owned by another open project.
It's part of issue 53216. It happens only in project with existing source, but with both - test and source folder. *** This issue has been marked as a duplicate of 53216 ***