This crawl has been paused by the search system..

I came across this funky error today while configuring a client's search service:

"This crawl has been paused by the search system while a new query server is added. After the new query server is online, the crawl will be resumed."

Now, I had not added a new query server to the farm so this was a bit of a mystery, and there were no solutions to be found on Google. On closer inspection of the Search Settings page, I noticed that the Propagation Status was "Propagating to new query server ([servername])". This server was added to the farm, and the query service added, several weeks ago.

Then I noticed that on the Search Administration screen the Server Status for the two query servers mentioned the C: drive, which was low on disk space. Turns out my script for starting the query service had not set the propagation location to the correct location, on the D: drive where there was plenty of space. The search service was trying to propagate the index to the C: drives, which had run out of space, hence it was hanging.

I changed the propagation location by running this command on the query servers:

stsadm -o osearch -propagationlocation "D:\Osearch"

After a few minutes the propagation status returned to Idle and I was able to run the crawl without any errors.