Is this upgrade error fatal?

 (gtk-update-icon-cache-3.0:19389): GdkPixbuf-WARNING **: Cannot open pixbuf loader module file '/usr/lib/x86_64-linux-gnu/gdk-pixbuf-2.0/2.10.0/loaders.cache': No such file or directory

This likely means that your installation is broken.
Try running the command
  gdk-pixbuf-query-loaders > /usr/lib/x86_64-linux-gnu/gdk-pixbuf-2.0/2.10.0/loaders.cache

Get this error while upgrading and updating just checking to make sure its not going to affect the operating system and the way it runs.

Solution 1:

Running the corresponding command will often not work because the binary is not in the PATH: you need to run it with an indication of the complete path, and also to run it as root:

sudo /usr/lib/x86_64-linux-gnu/gdk-pixbuf-2.0/gdk-pixbuf-query-loaders | sudo tee /usr/lib/x86_64-linux-gnu/gdk-pixbuf-2.0/2.10.0/loaders.cache

(may need to be adapted for your install)

More information in this Debian bug report.