Search can return this error due to various reasons “Search has encountered a problem that prevents results from being returned. If the issue persists, please contact your administrator” but this will be certainly come if there is an error in one of the search components.
If you check in ULS log you will see this error ” Cannot plan query for index system. Index fragment ‘0’ has no available cells.”
This error indicates that there is an error in index partition and you should see a yellow warning exclamation in Central Admin as shown below
If your error meets all these criteria then you have the same issue. If you look at other articles regarding then 90% of articles will mention to do an index reset and do a full crawl which will definitely fix the issue but this should be your last option and not the first one in a production environment.
To fix the issue we should look at clearing configuration cache on the server where index partition is being stored.
The steps to clear configuration cache is very well documented and can be found below
But doing these steps might not fix the issue so follow below instructions
- Try first clearing configuration cache and check if error gets fixed
- If not then again do the same steps but this time also restart SharePoint Search Service before you restart the SharePoint Timer Service
- If this also does not work then try to restart the server after step 1, restarting server in Production environment is not advisable during office hours so do it in planned manner
- If this also does not work then we are left with no other option but do an index reset and do a full crawl, use steps documented on Microsoft site Perform index reset
Also note that during these operations if any incremental or full crawl was going on you need to let it finish to make a call if above has fixed the issue. We observed that issue goes away only when crawl has finished.
Above strategy should work in most cases if not then reach out to us and we can help.