If you’ve ever seen the words “The following packages have been kept back” you’ll know it can be pretty frustrating. You’ve told it to update, why isn’t it updating?
This occurs because the package has had it’s dependencies changed. It’s either going to install more or uninstall software the new version doesn’t need. A lot of replies will tell you to do a dist-upgrade.
This is a very bad idea, unless you know what you are doing. This will cause a LOT of changes to your system, and it’s not massively unusual to see it prevent a system running until you sort out a raft of post dist-upgrade issues. Now, some people will argue that you should always dist-upgrade, and deal with issues as they crop up, and while there’s merit to this, you can’t do it on a production system, especially just because you need to upgrade a package.
What’s the solution?
This will then follow up with the usual explanation of which packages will be added or removed. Type in “y” like you normally do, and it will install/uninstall/upgrade your packages. Done.