Fix to "Error Value: Error: rpmdb open failed"

"An internal system error has occured

A problem that we were not expecting has occured.
Please report this bug in your distribution bugtracker with
the error description"
Under more details it says:

Error Type: <class 'yum.Errors.YumBaseError'>
Error Value: Error: rpmdb open failed
File : /usr/share/PackageKit/helpers/yum/yumBackend.py, line 3612, in <module>
main()
File : /usr/share/PackageKit/helpers/yum/yumBackend.py, line 3608, in main
backend = PackageKitYumBackend('', lock=True)
File : /usr/share/PackageKit/helpers/yum/yumBackend.py, line 264, in __init__
self.doLock()
File : /usr/share/PackageKit/helpers/yum/yumBackend.py, line 350, in doLock
self.yumbase.doLock(YUM_PID_FILE)

File : /usr/lib/python2.7/site-packages/yum/__init__.py, line 1585, in doLock
if self.conf.uid != 0:
File : /usr/lib/python2.7/site-packages/yum/__init__.py, line 831, in <lambda>
conf = property(fget=lambda self: self._getConfig(),
File : /usr/lib/python2.7/site-packages/yum/__init__.py, line 277, in _getConfig
startupconf = config.readStartupConfig(fn, root)
File : /usr/lib/python2.7/site-packages/yum/config.py, line 859, in readStartupConfig
startupconf.releasever = _getsysver(startupconf.installroot, startupconf.distroverpkg)
File : /usr/lib/python2.7/site-packages/yum/config.py, line 1004, in _getsysver
raise Errors.YumBaseError("Error: " + str(e))

Solution:

su -
rm -f /var/lib/rpm/__db*
rpm --rebulddb
yum upgrade