- In Central Administration on the Search Administration page: "Unable to retrieve topology component health states. This may be because the admin component is not up and running".
- In the ULS logs: "All query processing components are in 'failed' status".
- On Search pages: "Something went wrong".
- Etc, etc.
I had tweaked the memory limit for the NodeRunner.exe process. I did this because this was my development environment and at the time I had no need for search for I wanted to increase performance as much as possible. However, I had forgotten about this and thus my problems began.
In the NodeRunner configuration file (located at: C:\Program Files\Microsoft Office Servers\15.0\Search\Runtime\1.0\NodeRunner.exe.config) there is a property called 'memoryLimitMegabytes' which you can use to control how much memory the processes can consume. I had reduced this number (changed it from 0, since 0 is unlimited) to 100MB. This turned out to be way too low and caused all my search components to fail.
If you have not modified your NodeRunner configuration file, you should check this post for some guidance on hotfixes: http://social.technet.microsoft.com/Forums/en-US/sharepointitpropreview/thread/50acc2b8-dd56-4d5a-a660-dffa325ef807/