Error
Error Code:
55P02
PostgreSQL Error 55P02: Cannot Change Runtime Parameter
Description
Error 55P02 in PostgreSQL indicates that a runtime configuration parameter cannot be modified because the database system or the affected object is not in the necessary state. This typically occurs when attempting to alter a setting that requires a database restart, a different session context, or if the parameter is immutable under current conditions.
Error Message
cant change runtime param
Known Causes
4 known causesParameter Requires Server Restart
Many critical PostgreSQL parameters, like `shared_buffers` or `wal_level`, can only be altered by restarting the database server for changes to take effect.
Session-Specific or Immutable Parameter
Some parameters are designed to be set only at the session level, while others are fixed for the lifetime of the server process and cannot be changed dynamically.
Conflicting Configuration or Object State
The desired parameter change might conflict with other active settings, or the current state of a database object prevents its modification.
Parameter Locked by Active Processes
Active database connections, transactions, or ongoing operations might temporarily lock a parameter, preventing its modification until they are completed.
Solutions
3 solutions available1. Restart PostgreSQL Service easy
A simple restart often resolves transient issues preventing parameter changes.
1
Identify the PostgreSQL service name. This can vary based on your operating system and installation method.
sudo systemctl status postgresql # For systemd-based systems (most modern Linux)
sudo service postgresql status # For older init.d systems2
Restart the PostgreSQL service.
sudo systemctl restart postgresql
# OR
sudo service postgresql restart3
Attempt to change the runtime parameter again using `ALTER SYSTEM SET` or by modifying `postgresql.conf` and reloading.
ALTER SYSTEM SET your_parameter = 'new_value';
SELECT pg_reload_conf();2. Modify `postgresql.conf` Directly and Reload medium
Directly editing the configuration file and reloading is a reliable way to apply changes.
1
Locate your `postgresql.conf` file. The location can be found by querying PostgreSQL itself or checking common installation paths.
SHOW config_file;2
Open the `postgresql.conf` file with a text editor that has sufficient privileges (e.g., `sudo nano /etc/postgresql/14/main/postgresql.conf`).
sudo nano /path/to/your/postgresql.conf3
Find the line corresponding to the parameter you want to change. Uncomment it if it's commented out (starts with '#') and set the desired value.
#shared_buffers = 128MB
shared_buffers = 256MB4
Save the changes to `postgresql.conf`.
5
Reload the PostgreSQL configuration to apply the changes without restarting the service.
SELECT pg_reload_conf();3. Check for System Constraints or Permissions advanced
Ensure no external factors or insufficient permissions are blocking the parameter change.
1
Verify that the parameter you are trying to change is indeed a runtime parameter that can be modified. Some parameters are compile-time or require a full restart.
SELECT name, context FROM pg_settings WHERE name = 'your_parameter_name';2
Confirm that the PostgreSQL user running the process has the necessary write permissions to the `postgresql.conf` file if you are editing it directly.
ls -l /path/to/your/postgresql.conf3
If using `ALTER SYSTEM`, ensure the user executing the command has the `SUPERUSER` privilege or the `ALTER ROLE ... SET` privilege for the specific parameter.
ALTER USER your_username SUPERUSER;
-- OR, more granularly:
ALTER ROLE your_username SET your_parameter TO 'new_value'; -- This might still require reload.4
Review PostgreSQL logs for any other related errors or warnings that might indicate a deeper issue.
SHOW log_directory;