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Fix: “Postmaster Running” Error During PostgreSQL Upgrade

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Fix: “Postmaster Running” Error During PostgreSQL Upgrade

Error:

Upgrading PostgreSQL can sometimes be tricky — especially when moving between major versions like PostgreSQL 14 to 15. One common issue many DBAs face is the error:

“There seems to be a postmaster servicing the new cluster. Please shutdown that postmaster and try again.”

Understanding Common PostgreSQL Upgrade and Connection Issues

PostgreSQL is one of the most reliable and powerful open-source databases, widely used for enterprise data management and analytics. Whether you’re managing your PostgreSQL online environment or performing an on-prem upgrade, it’s important to understand how the database handles connections and services.

When working with PostgreSQL, administrators often use the psql postgres command-line utility — a powerful tool that allows you to interact directly with your database. From creating roles to executing SQL queries, psql is at the core of PostgreSQL management and troubleshooting.

However, during upgrades or configuration changes, you may face issues such as:

  • FATAL: password authentication failed for user 'postgres'

  • There seems to be a postmaster servicing the new cluster

These errors typically occur due to authentication conflicts or active PostgreSQL services running during migration or upgrade processes.

In this blog, we’ll explore how to identify, troubleshoot, and fix these issues efficiently — whether you’re running PostgreSQL online or managing a local instance using psql postgres. You’ll also learn best practices to ensure smooth upgrades and reliable connections for your database environment.

There seems to be a postmaster servicing the new cluster.
Please shutdown that postmaster and try again.
Failure, exiting
1 . stop the old PostgreSQL 14 service

To ensure no cluster is running during the upgrade:

sudo systemctl stop postgresql-14
2 . Double-check no PostgreSQL processes are running
ps -ef | grep postgres

If you still see any postgres process (for version 14 or 15), kill them manually:

sudo kill -9 <PID>
3 . Now re-run your pg_upgrade command

Once both clusters are stopped, run the same command again:

/usr/pgsql-15/bin/pg_upgrade \
--old-bindir=/usr/pgsql-14/bin \
--new-bindir=/usr/pgsql-15/bin \
--old-datadir=/var/lib/pgsql/14/data \
--new-datadir=/var/lib/pgsql/15/data

Conclusion

Archive Mode in PostgreSQL is more than just a backup feature — it’s the foundation of a reliable recovery strategy. Whether you’re learning through a PostgreSQL Course, practicing via a PostgreSQL Learn Online module, or advancing your skills to Learn PostgreSQL DBA, mastering this configuration ensures your data remains safe, consistent, and recoverable at all times.

Continuous learning and hands-on implementation are key to becoming a confident PostgreSQL professional.

At Learnomate Technologies, we make sure you not only understand such cutting-edge features but also know how to implement them in real-world projects. Whether you’re a beginner looking to break into the database world or an experienced professional upgrading your skillset—we’ve got your back with the most practical, hands-on training in Oracle technologies.

📺 Want to see how we teach? Head over to our YouTube channel for insights, tutorials, and tech breakdowns: 👉 www.youtube.com/@learnomate

🌐 To know more about our courses, offerings, and team: Visit our official website: 👉 www.learnomate.org

💼 Let’s connect and talk tech! Follow me on LinkedIn for more updates, thoughts, and learning resources: 👉 https://www.linkedin.com/in/ankushthavali/

📝 If you want to read more about different technologies, Check out our detailed blog posts here: 👉 https://learnomate.org/blogs/

Let’s keep learning, exploring, and growing together. Because staying curious is the first step to staying ahead.

Happy learning!

ANKUSH😎

 

 

 

 

 

 

 

 

 

 

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