After composer dumpautoload show InstalledVersions" not found

Question

I have a TYPO3 v11 project The project was running fine and i'm working on a new plugin source code. After a "composer dumpautoload" command in the console, The project found this error:

Fatal error: Uncaught Error: Class "Composer\InstalledVersions" not found 
 TYPO3\CMS\Core\Core\SystemEnvironmentBuilder::run(0, 1) #3 /var/www/html/web/index.php(21): {closure}() #4 {main} thrown in /var/www/html/web/typo3/sysext/core/Classes/Core/Environment.php on line 137

Any idea how i can get back the project working again ? Thanks

Answer 1

It is very likely that you did invoke Composer 1.x where Composer\InstalledVersions does not exist.

This was added with Composer 2.x so make sure your Composer version is up-to-date.