this problem appeared again after I ran a composer update
- Updating symfony/yaml (v3.4.42 => v3.4.43): Loading from cache
- Updating symfony/translation (v3.4.42 => v3.4.43): Loading from cache
- Updating symfony/event-dispatcher (v4.4.10 => v4.4.11): Loading from cache
- Updating symfony/console (v4.4.10 => v4.4.11): Loading from cache
- Updating symfony/filesystem (v4.4.10 => v4.4.11): Loading from cache
- Updating symfony/config (v3.4.42 => v3.4.43): Loading from cache
- Updating s9e/text-formatter (2.7.2 => 2.7.3): Loading from cache
- Updating monolog/monolog (1.25.4 => 1.25.5): Loading from cache
- Updating league/flysystem (1.0.69 => 1.0.70): Loading from cache
- Updating symfony/debug (v4.4.10 => v4.4.11): Loading from cache
- Updating symfony/finder (v4.4.10 => v4.4.11): Loading from cache
- Updating symfony/mime (v5.1.2 => v5.1.3): Loading from cache
- Updating symfony/http-foundation (v4.4.10 => v4.4.11): Loading from cache
- Updating symfony/process (v4.4.10 => v4.4.11): Loading from cache
- Updating symfony/css-selector (v5.1.2 => v5.1.3): Loading from cache
- Updating jslirola/flarum-ext-login2seeplus (v0.1.4 => v0.1.5): Downloading (100%)
- Updating kyrne/shout (0.1.14 => 0.1.16): Downloading (100%)
- Updating reflar/doorman (0.1.5 => 0.1.6): Downloading (100%)
- Updating zerosonesfun/elint (1.5 => 1.6): Downloading (100%)
- Updating league/oauth2-client (2.4.1 => 2.5.0): Loading from cache
- Updating league/oauth2-facebook (2.0.1 => 2.0.2): Loading from cache
- Updating fgribreau/mailchecker (v3.3.10 => v3.3.11): Downloading (100%)
- Updating dasprid/enum (1.0.0 => 1.0.1): Downloading (100%)
- Updating irony/flarum-ext-github-upload dev-master (095114a => 982cc5c)
After these updated, the forum appeared to be as if no extensions worked, but the admin panel works the fine.