Hi @Ani_Ghoghoberidze , welcome to the Percona forums!
First off our apologies for not having answered your question for 2 weeks. This was simply missed in our queue, usually we respond within hours (if not minutes) to new posts.
Regarding your error, can you tell us:
What version of ProxySQL are you running?
What version of PMM Server and PMM Client are you using?
What was the configuration command you used to set up ProxySQL i.e. pmm-admin add proxysql …
This is very strange as ProxySQL can’t really work properly without runtime_mysql_servers table…