Unable to create backup in Plesk via the Acronis Backup extension: version `GLIBCXX_3.4.26' not found

Plesk for Linux kb: technical ext: acronis

Applicable to:

After updating Plesk Obsidian to version 18.0.40, Acronis backup fails with the following error:

PLESK_ERROR: Failed to execute command '/usr/lib/Acronis/BackupAndRecovery/webcpprecapture: /usr/bin/sw-engine: /usr/lib/Acronis/system_libs/8.2.1/libstdc++.so.6: version `GLIBCXX_3.4.26' not found (required by /usr/bin/sw-engine)
Acronis console shows the following error message:

PLESK_ERROR: Cannot protect a device with assigned quota
Protection plan 'webcp' has been revoked from 'server.example.com' due to a licensing issue.

Acronis agent bug has been fixed in Acronis agent version 15.0 28610.

Update Acronis agent using the steps below:

Log into Plesk.
Go to Acronis Backup > Go to backup console. Enter credentials from the Acronis Backup console if required.
In the Acronis Backup console go to Settings > Agents.
In the list of machines select the one with outdated agent versions. They will be marked with an orange exclamation mark.

Note: The machines must be online.
Click Update agent. After updating make sure there are no unset directives that were previously configured as follows 69808: Acronis Backup extension for Plesk: Backup fails after Plesk update to version 18.0.40:

If update is not possible for some reason, apply

manual workaround:

Connect to the Plesk server via SSH.
Open the file /usr/lib/Acronis/BackupAndRecovery/webcpprecapture in a text editor. In this example, we are using the vi editor:

# vi /usr/lib/Acronis/BackupAndRecovery/webcpprecapture
Add the following lines:

CONFIG_TEXT: unset LD_LIBRARY_PATH
unset LD_PRELOAD
Save the changes and close the file.

Apply the following steps additionally, if Acronis agent version is 28323 (version can be checked in Acronis console).

Connect to the Plesk server via SSH.
Download the patched libwebcp_agent.so file:

# wget https://plesk.zendesk.com/hc/article_attachments/12376927359895/libwebcp_agent.so
Rename the original file:

# mv /usr/lib/Acronis/BackupAndRecovery/libwebcp_agent.so /usr/lib/Acronis/BackupAndRecovery/libwebcp_agent.so_backup
Move the downloaded file to the Acronis directory:

# mv libwebcp_agent.so /usr/lib/Acronis/BackupAndRecovery
Restart the Acronis service:

# service acronis_mms restart
Verify that Plesk is detected using the command:

Note: It make take a couple of minutes to take effect.

# acropsh -m dmldump -s mms -vs InstanceManagement::Instance | grep InstalledApplication

('.Parameters.InstalledApplication', 'item_string', 'Plesk'),
('.Parameters.InstalledApplication^Searchable', 'nil', None),