SharePoint 2010 Search – The search request was unable to connect to the Search Service

I finally found the answer here Sharepoint 2010 - The search request was unable to connect to the Search Service.

There can be a couple of different reasons for this error message, such as ensuring that the right service account is running the Search Windows Service, however there is one quick thing to check that might fix your issue.

1. Goto Central Administration
2. Application management
3. Manage Web Applications
4. Select the web application
5. Click on Service Connections
6. Ensure that the search application you configured is checked in this list.

If you go to edit your web app in central admin you will see that there is a button along the top called "Service Connections". Please ensure that your search app is selected in the form that pops up.

I've now got the search service running on my SharePoint Foundation 2010 Installation. Here's what I did:

1. In Central Administration, go to System Settings->Services on Server. (Note: Prior to this step - no WSS_Search_* database existed on the server)
2. Select the SharePoint Foundation Search service and click Start
3. Enter and/or confirm the settings on the Search service page
4. Press Start to start the service
5. Go to Manage Content Databases
6. For each content database in the SharePoint site - assign the correct search server (Note: This option was greyed out until after I started the service in "CA->Services on Server")

At this point search is now enabled on the server. I've verified that search is working correctly. However, I do note that the search service still does not appear in the CA->Manage Service Applications list)