I frequently get asked about the error:

So this article is to answer all questions in a time.

I don’t know why, but that grml kernel has a version number of grml.02 (other kernel versions are also affected). This version string doesn’t meet the criteria for version numbers because it doesn’t start with a digit. So dpkg is correctly warning. This warning is not critical, you might ignore it without any consequences, or you can install a newer one. Kernel with corrected version numbers can be found in grml-testing , so add the following to your /etc/apt/sources.list.d/grml.list :

and you’ll find for example the new 2.6.38 kernel. Just for those lazy guys:

So, have fun with your new kernel :-P