Hey #Drupal 8 #D8 #Composer friends, I'm having a weird composer issue:
Admin pages suddenly crash, seemingly out of the blue:
```
UnexpectedValueException: Invalid version string "main" in Composer\Semver\VersionParser->normalize()
```
It seems like Drupal is trying to see if there are core updates (>= 8.9.20), and then receives a "main" version identifier that composer can't deal with?
Possibly related to the new "main" branching scheme in D11 pushed 2 hours ago?
There does seem to be an issue with the new "main" Drupal core branch introduced today:
It throws an UnexpectedValueException in Composer's VersionParser, called by Core's getPossibleCoreUpdateVersions()...
Known issue, being discussed here: https://www.drupal.org/project/drupal/issues/3567483
If your #Drupal 8/9/10 site is crashing on /admin/ pages due to the new "main" branching scheme in D11, a simple drush cache rebuild won't be enough.
This will do the trick:
```
drush php:eval "Drupal::service('update.manager')->refreshUpdateData()"
```
