composer update after updating php version failed?

running # composer update after upgrading php on server gives out following error..

Installing doctrine/event-manager (1.1.1): Extracting archive
Install of doctrine/event-manager failed
Installing doctrine/cache (1.10.2): Extracting archive
Install of doctrine/cache failed

Install of webmozart/assert failed
Installing dragonmantank/cron-expression (v3.1.0): Extracting archive
Install of dragonmantank/cron-expression failed
Installing symfony/polyfill-php80 (v1.22.1): Extracting archive
Install of symfony/polyfill-php80 failed



  [ErrorException]          
  Undefined index: process