Adblock Plus update failure

[none]

Adblock Plus version:
current (already installed): 1.8.11
fails to install (update failure): 1.8.12

which browser you are using (with version number):
Safari: Version 6.2.3 (8537.85.12.18)

which operating system is used:
OSX Mountain Lion (10.8.5)

Other extensions:
1Password 4.2.5
Blur 4.7.1505
JavaScript Blacklist 1.0.1
WOT 2.0.17

Exact description of the steps that need to be followed to see the bug:
Every so often Safari tries to update installed extensions. When it tries to update Adblock Plus the update fails (Safari displays a dialog saying the update can't be done).
Trying to update manually also fails with the same dialog.

Exact description of what happens and what you think is wrong:
What happens is described in the previous section. I have no idea what's wrong.

[mapx]

Could you see if there are errors in the console ?
(how to see the console in safari: http://superuser.com/questions/635917/w ... n-safari-6 )

[none (not registered)]

There are no errors in either the Safari or OS X console (even after I manually forced an update).

For what it's worth (not much) the Safari dialog (untitled) contains the following content:

Safari can't install this extension
An error occurred while installing the extension
"Adblock Plus".

The dialog has an "OK" button to dismiss it.