1. Check the PostgreSQL log files for any errors or warnings that may be related to the issue.

$ tail -f /var/log/postgresql/postgresql-55000.log

2. Check the PostgreSQL configuration files for any settings that may be causing the issue

$ grep -i '55000' /etc/postgresql/9.6/main/postgresql.conf3.

Check the PostgreSQL system tables for any inconsistencies that may be causing the issue.

$ psql -c "SELECT * FROM pg_stat_activity WHERE datname = 'postgres';"

4. Check the PostgreSQL system processes for any issues that may be causing the issue

$ ps aux | grep postgres

5. Check the PostgreSQL system memory for any issues that may be causing the issue.

$ free -m

6. Check the PostgreSQL system disk space for any issues that may be causing the issue.

$ df -h

7.  Check the PostgreSQL system network connections for any issues that may be causing the issue

$ netstat -an | grep 5432

8. Once the issue has been identified, take the necessary steps to fix the issue.

9. After the issue has been fixed, it is recommended to use an automated database observability tool to monitor and fix the PostgreSQL 55000 in question. This tool can provide real-time insights into the performance and health of the database, as well as alerting when issues arise. It can also provide detailed metrics and logs to help diagnose and fix any issues quickly.