You are using PhpStorm’s own built-in web server, which has some issues right now (especially with POST requests, e.g. WEB-17317).
The solution is to use your own proper web server (Apache/IIS/nginx/whatever).
- Define Deployment entry.
In place
type should be fine, as long as your Apache/IIS can serve files from that location; otherwise either configure web server to be able to do that .. or use another type of deployment (e.g.Local or Mounted Folders
for IDE to copy files to another location for you) - Configure it (provide desired URL etc)
- Mark it as Default for this project
Now IDE will use that base URL when you will use Open in Browser
or Run/Debug actions (NOTE: it will not affect any existing Run/Debug Configurations — only future ones; you will have to update your current Run/Debug Configurations manually).