composer install error
```
$ composer require cboden/ratchet 
Using version ^0.4.1 for cboden/ratchet                                             
./composer.json has been updated
Loading composer repositories with package information
Updating dependencies (including require-dev)         
Your requirements could not be resolved to an installable set of packages.

  Problem 1
    - Conclusion: remove react/promise v2.5.1
    - Conclusion: don't install react/promise v2.5.1
    - react/socket v0.8.12 requires react/promise ^2.6.0 || ^1.2.1 -> satisfiable by react/promise[v1.2.1, v2.6.0, v2.7.0, v2.7.1].
    - react/socket v1.0.0 requires react/promise ^2.6.0 || ^1.2.1 -> satisfiable by react/promise[v1.2.1, v2.6.0, v2.7.0, v2.7.1].
    - react/socket v1.1.0 requires react/promise ^2.6.0 || ^1.2.1 -> satisfiable by react/promise[v1.2.1, v2.6.0, v2.7.0, v2.7.1].
    - react/socket v1.2.0 requires react/promise ^2.6.0 || ^1.2.1 -> satisfiable by react/promise[v1.2.1, v2.6.0, v2.7.0, v2.7.1].
    - Can only install one of: react/promise[v1.2.1, v2.5.1].
    - Can only install one of: react/promise[v2.6.0, v2.5.1].
    - Can only install one of: react/promise[v2.7.0, v2.5.1].
    - Can only install one of: react/promise[v2.7.1, v2.5.1].
    - Installation request for react/promise (locked at v2.5.1) -> satisfiable by react/promise[v2.5.1].
    - Installation request for cboden/ratchet ^0.4.1 -> satisfiable by cboden/ratchet[v0.4.1].
    - Conclusion: don't install react/socket v0.4.6|install react/socket v0.8.12|install react/socket v1.0.0|install react/socket v1.1.0|install react/socket v1.2.0
    - Conclusion: remove react/socket v0.4.6|install react/socket v0.8.12|install react/socket v1.0.0|install react/socket v1.1.0|install react/socket v1.2.0
    - cboden/ratchet v0.4.1 requires react/socket ^1.0 || ^0.8 || ^0.7 || ^0.6 || ^0.5 -> satisfiable by react/socket[v0.5.0, v0.5.1, v0.6.0, v0.7.0, v0.7.1, v0.7.2, v0.8.0, v0.8.1, v0.8.10, v0.8.11, v0.8.12, v0.8.2, v0.8.3, v0.8.4, v0.8.5, v0.8.6, v0.8.7, v0.8.8, v0.8.9, v1.0.0, v1.1.0, v1.2.0].
    - Can only install one of: react/socket[v0.5.0, v0.4.6].
    - Can only install one of: react/socket[v0.5.1, v0.4.6].
    - Can only install one of: react/socket[v0.6.0, v0.4.6].
    - Can only install one of: react/socket[v0.7.0, v0.4.6].
    - Can only install one of: react/socket[v0.7.1, v0.4.6].
    - Can only install one of: react/socket[v0.7.2, v0.4.6].
    - Can only install one of: react/socket[v0.8.0, v0.4.6].
    - Can only install one of: react/socket[v0.8.1, v0.4.6].
    - Can only install one of: react/socket[v0.8.10, v0.4.6].
    - Can only install one of: react/socket[v0.8.11, v0.4.6].
    - Can only install one of: react/socket[v0.8.2, v0.4.6].
    - Can only install one of: react/socket[v0.8.3, v0.4.6].
    - Can only install one of: react/socket[v0.8.4, v0.4.6].
    - Can only install one of: react/socket[v0.8.5, v0.4.6].
    - Can only install one of: react/socket[v0.8.6, v0.4.6].
    - Can only install one of: react/socket[v0.8.7, v0.4.6].
    - Can only install one of: react/socket[v0.8.8, v0.4.6].
    - Can only install one of: react/socket[v0.8.9, v0.4.6].
    - Installation request for react/socket (locked at v0.4.6) -> satisfiable by react/socket[v0.4.6].


Installation failed, reverting ./composer.json to its original content.
```