Package babel Error: Unknown option `francais'

The complete error message is:

! Package babel Error: Unknown option `francais'. Either you misspelled it
(babel)                or the language definition file francais.ldf was not found.

Package file babel.sty supports francais since a very long time, thus the second line of the error message applies very likely:

The organization of the babel language files has recently changed. The language files (.ldf, ...) go into separate TeX distribution packages. For example, option francais loads frenchb.ldf:

• TeX Live puts the latter in the distribution package babel-french. It needs to be installed, if you are using tlmgr, the package manager of TeX Live.

• In Ubuntu saucy there is a package texlive-lang-french that contains frenchb.ldf (file list). Install it, if you are using TeX Live of Ubuntu.

I had the same error while trying to generate the pdf files from lyx. I did run sudo apt-get install texlive-lang-french and the error was resolved. Now working fine

Update: These packages have become obsolete; texlive-lang-european should be installed now:

sudo apt-get install texlive-lang-european

Exactly same issue here for various languages like: \usepackage[dutch]{babel}

A way of solving: Open: Ubuntu Software Center and install: texlive-lang-all

But what still changed is that in case you change the language in the \usepackage[english]{babel} you have to remove the temporary latex files before latex-ing again. But with that remark every works again as before.