I had to reinstalled my local Sitecore instance and when I tried to load some pages that are using JSS / Headless Dictionary Service, I was surprised with 404, failed requests to it.
I have received this exception:
{"Message":"No HTTP resource was found that matches the request URI 'http://chorpo.sc/sitecore/api/jss/dictionary/MyApp/en/?sc_apikey=<HereIsMyApiKey>'.","MessageDetail":"No type was found that matches the controller named 'DictionaryService'."}
At first I was wondering what is happening…
Solution
- I have stopped Internet Information Services (IIS)
- Navigated to C:\Windows\Microsoft.NET\Framework64\v4.0.30319\Temporary ASP.NET Files\root
- Deleted all MS-ApiControllerTypeCache.xml under subsubfolder UserCache in each subsubfolder
- so for example C:\Windows\Microsoft.NET\Framework64\v4.0.30319\Temporary ASP.NET Files\root\xxxxx\xxxxx\UserCache\MS-ApiControllerTypeCache.xml

And that was it.
All problems were resolved!
