Hi,

Headless mode (and book import from the gui which seems to depend on headless mode for some books) fails when using qt 5.7 (with the Fedora calibre-2.68.0 pkgs on Fedora 25), the error reported is:

"
This application failed to start because it could not find or load the Qt platform plugin "headless"
in "/usr/lib64/calibre/calibre/plugins".

Available platform plugins are: eglfs, linuxfb, minimal, minimalegl, offscreen, xcb.

Reinstalling the application may fix this problem.
"

I've managed to hack around this (fixing using calibre under X at least) with this:

--- /usr/lib64/calibre/calibre/gui2/__init__.py~ 2016-09-17 17:58:30.000000000 +0200
+++ /usr/lib64/calibre/calibre/gui2/__init__.py 2016-09-25 15:02:29.831338885 +0200
@@ -876,10 +876,7 @@
         self.file_event_hook = None
         if override_program_name:
             args = [override_program_name] + args[1:]
- if headless:
- if not args:
- args = sys.argv[:1]
- args.extend(['-platformpluginpath', sys.extensions_location, '-platform', 'headless'])
+ headless = False
         self.headless = headless
         qargs = [i.encode('utf-8') if isinstance(i, unicode) else i for i in args]
         self.pi = plugins['progress_indicator'][0]
@@ -1186,6 +1183,7 @@
 _ea_lock = Lock()

 def ensure_app(headless=True):
+ headless = False
     global _store_app
     with _ea_lock:
         if _store_app is None and QApplication.instance() is None:

Which allows me to import books again. I realize this is a useless fix, but it proves that the problem is with headless and that calibre works fine otherwise.

I've filed an upstream bug for this here:

https://bugs.launchpad.net/calibre/+bug/1627494

Hopefully upstream will fix this soon, if not we should probably use my hack to at least get the gui to work properly on F25.