Composer installation/update fails on a Plesk server: Allowed memory size of X bytes exhausted

Kuzma Ivanov

Updated January 13, 2026 19:06

Plesk for Linux kb: technical ABT: Group B

Applicable to:

Plesk for Linux

Symptoms

When installing or updating Composer in Plesk or via a command-lin interface, the operation fails with the error message:

PLESK_ERROR: PHP Fatal error: Allowed memory size of X bytes exhausted (tried to allocate Y bytes) in phar:///usr/lib/plesk-9.0/composer.phar/src/Composer/DependencyResolver/Rule2Literals.php on line 48

Cause

Memory limit is insufficient for Composer update.

Resolution

Using Plesk Composer extension

Log in to Plesk.
Go to Domains > example.com > PHP Composer > Environment variables.
Click Specify under Environment variables.
Add the following environment variable:

CONFIG_TEXT: memory_limit = 2048M

Note: Set memory_limit to -1 to make it unlimited.

If the command fails with the same error, increase the memory_limit value or try to use this variable instead:

CONFIG_TEXT: COMPOSER_MEMORY_LIMIT = 2048M

Via a command-line interface

Connect to the Plesk server via SSH.
Run the command specifying the memory_limit:

# /opt/plesk/php/7.2/bin/php -d memory_limit=2048M /usr/lib/plesk-9.0/composer.phar update

If the command fails with the same error, increase the memory_limit value.