Error in composer auto load after server reboot

I had a very stable website running for months and after a server reboot I have a strange error:

2020/03/27 02:08:27 [error] 2543#2543: *81 FastCGI sent in stderr: "PHP message: PHP Fatal error:  Uncaught Error: Class 'Composer\Autoload\ComposerStaticInit3ca100a8fab39e9e5daefd9e83778204' not found in /var/www/html/SOMEWEBSITE/vendor/composer/autoload_real.php:33
Stack trace:
#0 /var/www/html/SOMEWEBSITE/vendor/autoload.php(7): ComposerAutoloaderInit3ca100a8fab39e9e5daefd9e83778204::getLoader()
#1 /var/www/html/SOMEWEBSITE/index.php(40): require('/var/www/html/k...')
#2 {main}
  thrown in /var/www/html/SOMEWEBSITE/vendor/composer/autoload_real.php on line 33" while reading response header from upstream, client:, server:, request: "GET / HTTP/1.1", upstream: "fastcgi://unix:/run/php/php7.3-fpm.sock:", host: ""

It was a hard reboot and I think something got corrupted. I fact I had to replace the whole /vendor directory to get rid of a syntax error in autoload_static.php.

I tried gpm self-upgrade then update without any effect.

Don’t what happened but I had to redeploy a complete grav directory to make it work.