If you are running the Fedora distribution and have recently been running into errors when attempting to install or update software, chances are you have been affected by a bug in the libdb package. The libdb software provides the database Fedora's package management utilities use to keep track of software packages. "There's a rather subtle and tricky bug in libdb (the database that RPM uses) which has been causing problems with upgrades from Fedora 24/25 to Fedora 26. The developers have made a few attempts to fix this, and testing this week had indicated that the most recent attempt - libdb-5.3.28-21 - was working well. We believed the fix needed to be applied both on the 'from' and the 'to' end of any affected transaction, so we went ahead and sent the -21 update out to Fedora 24, 25 and 26. Unfortunately it turns out that updating to -21 along with other packages can possibly result in a crash at the very end of the process, which in turn causes a (as it happens, minor and fully recoverable) problem in the RPM database." A longer explanation and a fix for the issue was published on the Fedora Magazine website.