You have double-clicked on a disk image, and macOS refuses. Here is what you can do to get that image to mount, even when it’s damaged.
xattred
The File menu has been tidied, and xattred can now save the one xattr selected or all of them to a text file.
This new version should run OK on El Capitan, but has no functional changes apart from that.
Hectic with SIP problems in High Sierra, the Meltdown and Spectre vulnerabilities, then iCloud Drive’s strange stripping of extended attributes.
Browse, cut/copy/paste, edit content, export as text, and more for any xattr attached to a folder or file in HFS+ and APFS, Sierra and High Sierra.
How to attach a metadata flag to a file or folder, to bring it under the protection of SIP.
Can now edit the content of existing xattrs, and create completely new ones, with arbitrary content.
Tweaked to see and open any file or folder, even inside bundles, and to fix a display glitch with binary property lists.
Now supports cut, copy and paste of any xattr between files or folders. Also adds quarantine flags, and reveals full content of most xattrs.
There’s something wrong with that file, which seems to keep crashing an app. When you can’t put your finger on what’s wrong, it’s likely to be a xattr problem.
The Eclectic Light Company 