When using composer update you can get following memory error: 

PHP Fatal error:  Allowed memory size of 1610612736 bytes exhausted (tried to allocate 67108864 bytes) in phar:///usr/bin/composer/src/Composer/DependencyResolver/Solver.php on line 220

Fatal error: Allowed memory size of 1610612736 bytes exhausted (tried to allocate 67108864 bytes) in phar:///usr/bin/composer/src/Composer/DependencyResolver/Solver.php on line 220

Check https://getcomposer.org/doc/articles/troubleshooting.md#memory-limit-errors for more info on how to handle out of memory errors.[





//find path to composer, for example /usr/bin/composer
which composer 
php -d memory_limit=2000M /usr/bin/composer update