discussion Guide Plesk Plesk Panel 500 PleskPMMResponseException Error – Fix Guide 2025

[CL4Y]

Plesk Panel users may encounter the 500 PleskPMMResponseException error during backup or restore operations.
This issue typically occurs when the Plesk Migration and Backup Manager (PMM) component fails to function properly.

One of the most common causes is that the system’s default Python version link has been modified.
If the path /usr/bin/python3 points to an incorrect or incompatible Python version, Plesk may throw this error.

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🔍 Root Cause of the Error​

Plesk requires specific Python versions (e.g., Python 3.6) to perform certain tasks.
If a system update changes the Python version or alters the symbolic link for /usr/bin/python3, Plesk components may stop working, resulting in an error similar to this:

500 PleskPMMResponseException
Unable to get response from Plesk Migration Manager.
Failed to parse response. Reason: Failed to read data from stream Process output:

Type	PleskPMMResponseException
Message	Failed to parse response. Reason: Failed to read data from stream Process output:
File	PMMConnector.php
Line	875

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✅ Solution Steps​

Follow the steps below to fix the issue quickly and restore Plesk’s normal operation:

1. Connect to Your Server via SSH​

Access your server using root privileges through SSH.

2. Check Python Symbolic Link​

Run the following command to verify where the python3 link points:

ls -l /usr/bin/python3

If /usr/bin/python3 points to a version other than python3.6 (for example python3.10), you’ll need to correct it.

3. Remove Incorrect Python Link​

unlink /usr/bin/python3

This command removes the existing symbolic link for python3.

4. Recreate the Correct Python Link​

ln -s /usr/bin/python3.6 /usr/bin/python3

This command re-establishes the python3 link to the python3.6 version installed on your system.

⚠️ Note: If python3.6 is not installed on your system, you’ll need to install it first.
In most Plesk-supported environments, this version is already available.

 

[CL4Y]

The 500 PleskPMMResponseException error is usually caused by a corrupted Python configuration in the system. This error can be safely resolved by redirecting to the correct Python version using the steps described above. It is particularly important to check this connection after manual Python updates or software installations.

Ensure that system components are working in harmony to keep your backup and migration processes running smoothly.