Updating dependencies (including require-dev)
Your requirements could not be resolved to an installable set of packages.
Problem 1
- Installation request for barryvdh/laravel-debugbar ^3.1 -> satisfiable by barryvdh/laravel-debugbar[v3.1.0].
- Conclusion: remove laravel/framework v5.4.36
- Conclusion: don't install laravel/framework v5.4.36
- barryvdh/laravel-debugbar v3.1.0 requires illuminate/session 5.5.x -> satisfiable by illuminate/session[v5.5.0, v5.5.16, v5.5.17, v5.5.2].
- don't install illuminate/session v5.5.0|don't install laravel/framework v5.4.36
- don't install illuminate/session v5.5.16|don't install laravel/framework v5.4.36
- don't install illuminate/session v5.5.17|don't install laravel/framework v5.4.36
- don't install illuminate/session v5.5.2|don't install laravel/framework v5.4.36
- Installation request for laravel/framework (locked at v5.4.36, required as 5.4.*) -> satisfiable by laravel/framework[v5.4.36].
Installation failed, reverting ./composer.json to its original content.
комментарий выше помог