I have a serious problem on Ubuntu-MATE 16.04.

My desktop flickers like a strobe light (doesn't stop), and all icons are white. (Icons also have a red "X" on them). This happened instantly as a result of installing & opening the ebook reader Calibre.

The background image at the greeter login page is also gone.

(The username & password boxes are still there -- but background is black -- so I can log in and issue terminal commands between flickers. The terminal autostarts, so it's already up.)

I can also access the virtual terminal.

Running sudo apt install --reinstall ubuntu-mate-desktop warned of 3 unmet dependencies:

  1. apturl ("but it is not installable"),

  2. compiz-plugins ("but it is not going to be installed"),

  3. ubuntu-mate-core ("but it is not going to be installed").

It also warned: "Unable to correct problems, you have held broken packages."

I created a 2nd user, where the problem is less severe: no flickering, just white icons. I'd like to start to troubleshoot from there.

On the 2nd-user account, the panel and menu icons are all white with the red X. The icons on the desktop are just white, with no X.

Graphics card is Nvidia GeForce GTS 450, driver 367.44.

The .xsession-errors file for the 2nd user has several "unrecognized image file formate" warnings like this:

(caja:4609): Gtk-WARNING: Error loading theme icon 'image-missing' for stock: Unrecognized image file format

… for several different apps. (Caja is MATE's Nautilus.)

and like these:

sys:1: Warning: /build/glib2.0-7IO_Yw/glib2.0-2.48.1/./gobject/gsignal.c:2635: instance '0x7fc16c00aa70' has no handler with id '21847'
mate-session[4217]: Gtk-WARNING: Error loading theme icon 'image-missing' for stock: Unrecognized image file format
Window manager warning: CurrentTime used to choose focus window; focus window may not be correct.
Window manager warning: Got a request to focus the no_focus_window with a timestamp of 0.  This shouldn't happen!
mate-screensaver: Fatal IO error 11 (Resource temporarily unavailable) on X server :0.

(It was suggested here (in 2009, at the bottom of the thread) that removing the .local dir from the home dir would solve the icons problem. So I did that for the 2nd user but it had no effect.)

(It was also suggested on a non-ubuntu forum that reinstalling librsvg would solve the problem. I didn't do that because, at least on MATE, librsvg2-2 has about a hundred dependencies.)

The full .xsession-errors file is here.

What I'd like to do, if possible, for starters, is restore the icons on the 2nd-user login.

Would anyone have suggestions of how to do that, and how I might get rid of the "unrecognized file format" warnings? Thanks.

  • It looks like two separate issues, one with DE being broken, and the other one is unmet dependencies. I'd be more concerned for the second one, because for a moment you can try another DE, and there's a possibility that reinstall would solve the problem. What happens if you do sudo apt install apturl? If it's installed, what does it say for sudo apt install --reinstall apturl? – Hi-Angel Sep 11 '16 at 20:23
  • Thanks for responding. Same output for both commands: Package apturl is not available, but is referred to by another package. This may mean that the package is missing, has been obsoleted, or is only available from another source E: Package 'apturl' has no installation candidate – Melvin Q. Watchpocket Sep 11 '16 at 23:17
  • Also: $ sudo apt install compiz-plugins . . . The following packages have unmet dependencies: compiz-plugins : Depends: compiz-core (= 1: but 1: is to be installed Depends: compiz-plugins-default (= 1: but 1: is to be installed E: Unable to correct problems, you have held broken packages._ – Melvin Q. Watchpocket Sep 11 '16 at 23:27
  • Also: ubuntu-mate-core : Depends: apturl but it is not installable E: Unable to correct problems, you have held broken packages. – Melvin Q. Watchpocket Sep 11 '16 at 23:29
  • My /etc/apt/sources.list file is here: (paste.ubuntu.com/23167160) – Melvin Q. Watchpocket Sep 12 '16 at 0:04

FIXED. I did a standard upgrade with the software updater and magically, after 3 weeks, this problem was instantly solved the second the upgrades came in. Unbelievable. I've been going crazy trying to fix this, and it happens by itself. Rather, I think it's because I added an ubuntu-mate ppa that I needed last night and didn't have for xenial. (NB There is NO checkmark to accept this answer. Is it because I answered my own question?)

  • There's no a ✓ because you're posting from different accounts. You may probably want to ask mods to merge them. – Hi-Angel Sep 13 '16 at 18:01

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