nether494 the following extensions are holding you back:

 fof/links 0.3.0 requires flarum/core (>=0.1.0-beta.12 <0.1.0-beta.14)
fof/sitemap 0.5.3 requires flarum/core (>=0.1.0-beta.13 <0.1.0-beta.14)
fof/stopforumspam 0.2.2 requires flarum/core (>=0.1.0-beta.12 <0.1.0-beta.14)
fof/upload 0.10.1 requires flarum/core (>=0.1.0-beta.12 <0.1.0-beta.14)

I have not checked whether all of them have beta 15 compatibility. If they do, you could try replacing their version constraints in composer.json with *. The Extiverse helper can help you do that if needed https://discuss.flarum.org/d/25246-extiverse-helper

      clarkwinkelmann Removed now

      I have this

      [root]$ composer update --no-install --with-all-dependencie

      [Symfony\Component\Console\Exception\RuntimeException]
      The "--with-all-dependencie" option does not exist.

      update [--with WITH] [--prefer-source] [--prefer-dist] [--dry-run] [--dev] [--no-dev] [--lock] [--no-install] [--no-autoloader] [--no-scripts] [--no-suggest] [--no-progress] [-w|--with-dependencies] [-W|--with-all-dependencies] [-v|vv|vvv|--verbose] [-o|--optimize-autoloader] [-a|--classmap-authoritative] [--apcu-autoloader] [--apcu-autoloader-prefix APCU-AUTOLOADER-PREFIX] [--ignore-platform-req IGNORE-PLATFORM-REQ] [--ignore-platform-reqs] [--prefer-stable] [--prefer-lowest] [-i|--interactive] [--root-reqs] [--] [<packages>]...

      [root]$ composer install --prefer-dist --no-dev -a
      Installing dependencies from lock file
      Verifying lock file contents can be installed on current platform.
      Nothing to install, update or remove
      Generating optimized autoload files
      Carbon 1 is deprecated, see how to migrate to Carbon 2.
      https://carbon.nesbot.com/docs/#api-carbon-2
      You can run './vendor/bin/upgrade-carbon' to get help in updating carbon and other frameworks and libraries that depend on it.
      21 packages you are using are looking for funding.
      Use the composer fund command to find out more!
      [root]$ composer why-not flarum/core v0.1.0-beta.15
      flarum/core v0.1.0-beta.15 requires components/font-awesome (5.14.0)
      flarum/flarum - does not require components/font-awesome (but 5.9.0 is installed)
      flarum/core v0.1.0-beta.15 requires dflydev/fig-cookies (2.0.1)
      flarum/flarum - does not require dflydev/fig-cookies (but v1.0.2 is installed)
      flarum/core v0.1.0-beta.15 requires illuminate/bus (6.0)
      flarum/flarum - does not require illuminate/bus (but v5.7.28 is installed)
      flarum/core v0.1.0-beta.15 requires illuminate/cache (6.0)
      flarum/flarum - does not require illuminate/cache (but v5.7.28 is installed)
      flarum/core v0.1.0-beta.15 requires illuminate/config (6.0)
      flarum/flarum - does not require illuminate/config (but v5.7.28 is installed)
      flarum/core v0.1.0-beta.15 requires illuminate/container (6.0)
      flarum/flarum - does not require illuminate/container (but v5.7.28 is installed)
      flarum/core v0.1.0-beta.15 requires illuminate/contracts (6.0)
      flarum/flarum - does not require illuminate/contracts (but v5.7.28 is installed)
      flarum/core v0.1.0-beta.15 requires illuminate/database (6.0)
      flarum/flarum - does not require illuminate/database (but v5.7.28 is installed)
      flarum/core v0.1.0-beta.15 requires illuminate/events (6.0)
      flarum/flarum - does not require illuminate/events (but v5.7.28 is installed)
      flarum/core v0.1.0-beta.15 requires illuminate/filesystem (6.0)
      flarum/flarum - does not require illuminate/filesystem (but v5.7.28 is installed)
      flarum/core v0.1.0-beta.15 requires illuminate/hashing (6.0)
      flarum/flarum - does not require illuminate/hashing (but v5.7.28 is installed)
      flarum/core v0.1.0-beta.15 requires illuminate/mail (6.0)
      flarum/flarum - does not require illuminate/mail (but v5.7.28 is installed)
      flarum/core v0.1.0-beta.15 requires illuminate/queue (6.0)
      flarum/flarum - does not require illuminate/queue (but v5.7.28 is installed)
      flarum/core v0.1.0-beta.15 requires illuminate/session (6.0)
      flarum/flarum - does not require illuminate/session (but v5.7.28 is installed)
      flarum/core v0.1.0-beta.15 requires illuminate/support (6.0)
      flarum/flarum - does not require illuminate/support (but v5.7.28 is installed)
      flarum/core v0.1.0-beta.15 requires illuminate/validation (6.0)
      flarum/flarum - does not require illuminate/validation (but v5.7.28 is installed)
      flarum/core v0.1.0-beta.15 requires illuminate/view (6.0)
      flarum/flarum - does not require illuminate/view (but v5.7.28 is installed)
      flarum/core v0.1.0-beta.15 requires nesbot/carbon (2.0)
      flarum/flarum - does not require nesbot/carbon (but 1.39.1 is installed)
      flarum/core v0.1.0-beta.15 requires symfony/config (4.3.4)
      flarum/flarum - does not require symfony/config (but v3.4.47 is installed)
      flarum/core v0.1.0-beta.15 requires symfony/translation (4.3.4)
      flarum/flarum - does not require symfony/translation (but v3.4.47 is installed)
      flarum/core v0.1.0-beta.15 requires symfony/yaml (4.3.4)
      flarum/flarum - does not require symfony/yaml (but v3.4.47 is installed)

          nether494 if possible, try updating Composer, ideally to version 2.

          There might be an alternate command for older Composer versions, maybe someone will be able to post it.

            nether494 composer update --no-install --with-all-dependencie

            composer update --no-install --with-all-dependencies