Yum database is locked

When I do yum update I get the following error response:

One of the configured repositories failed (Unkown),
and yum doesn't have enough cached data to continue. At this point the
only
safe thing yum can do is fail. There are a few ways to work "fix" this:

1. Contact the upstream for the repository and get them to fix the problem.

2. Reconfigure the baseurl/etc. for the repository, to point to a working
   upstream. This is most often useful if you are using a newer
   distribution release than is supported by the repository (and the
   packages for the previous distribution release still work).

3. Run the command with the repository temporarily disabled
   yum –disablerepo= …

4. Disable the repository permanently, so yum won't use it by default. Yum
   will then just ignore the repository until you permanently enable it
   again or use –enablerepo for temporary usage:

   yum-config-manager –disable
   or
   subscription-manager repos –disable=

5. Configure the failing repository to be skipped, if it is unavailable.
   Note that yum will try to contact the repo. when it runs most commands,
   so will have to try and fail each time (and thus. yum will be be much
   slower). If it is a very temporary problem though, this is often a nice
   compromise:

   yum-config-manager –save –setopt=.skip_if_unavailable=true

   database is locked

I already did yum clean all, rm -f /var/lib/rpm/__db* and rpm --rebuilddb without any change.