Symptoms
Plesk update or upgrade fails with the following error found at
/var/log/plesk/install/autoinstaller3.log:Running Transaction Check
Fatal error during packages installation: Test Transaction Errors: file /usr/lib64/python3.6/site-packages/yaml/init.py from install of python36-PyYAML-3.13-1.el7.x86_64 conflicts with file from package python3-PyYAML-5.3-2.vl7.1.x86_64
file /usr/lib64/python3.6/site-packages/_yaml.cpython-36m-x86_64-linux-gnu.so from install of python36-PyYAML-3.13-1.el7.x86_64 conflicts with file from package python3-PyYAML-5.3-2.vl7.1.x86_64
Cause
There is a package conflict where a higher and not compatible version of a needed package is already installed.
Resolution
Connect to the server via SSH
Remove the conflicting package by name and version as found on the error, without removing any dependency as follows:
# rpm -e --nodeps python3-PyYAML-5.3-2.vl7.1.x86_64
Rerun Plesk upgrade:
# plesk installer