Unity wallpaper in precise overlays wallch wallpaper ...

Not exactly a Unity/wallch problem. Identified that this was due to a file whose name was not readable by wallch.

This was the file "Langelinie_Allé_by_SirPecanGum.jpg" from

https://launchpad.net/ubuntu/oneiric/+source/ubuntu-wallpapers/0.32.1/+files/ubuntu-wallpapers_0.32.1.tar.gz

Other files that created problems:
Floorboards_by_Dawid_Huczyński.jpg
Tie_My_Boat_by_Ray_García.jpg

It is all files with accents in the name. Output of locale:

locale
LANG=en_IN
LANGUAGE=en
LC_CTYPE=en_US.UTF-8
LC_NUMERIC="en_IN"
LC_TIME="en_IN"
LC_COLLATE=en_US.UTF-8
LC_MONETARY="en_IN"
LC_MESSAGES=en_US.UTF-8
LC_PAPER="en_IN"
LC_NAME="en_IN"
LC_ADDRESS="en_IN"
LC_TELEPHONE="en_IN"
LC_MEASUREMENT="en_IN"
LC_IDENTIFICATION="en_IN"
LC_ALL=

Hello Sachin, this has already been reported and fixed. The fix will be available at the next version!

For more info: https://bugs.launchpad.net/ubuntu/+source/wallch/+bug/977597

Hello there!
I've released a testing PPA (quite stable though) with some new features, which also solves the problems you had.
You can find it here:
https://launchpad.net/~wallch/+archive/3+

Specifically, current latest versions of this ppa are:
32-bit:
https://launchpad.net/~wallch/+archive/3+/+files/wallch_3.52-0ubuntu1_i386.deb
64-bit:
https://launchpad.net/~wallch/+archive/3+/+files/wallch_3.52-0ubuntu1_amd64.deb

You can add this ppa, so as to receive updates from it as well, as following:
sudo add-apt-repository ppa:wallch/3+
sudo apt-get update && sudo apt-get install wallch

I repeat that these are testing versions of Wallch that fix some bugs and have some new features, but it is logical to have some bugs. Please, if you find any, report it at: https://bugs.launchpad.net/wallpaper-changer/+filebug

Thanks a lot!