1. make sure "SharePoint server search" is running
$ss1 = get-spenterprisesearchserviceinstance -local
Stop-spenterprisesearchserviceinstance $ss1
Start-spenterprisesearchserviceinstance $ss1
Or try second option as bellow...
Run these steps
open the power-shell and run this command
Get-SPServiceInstance | ? {$_.TypeName -eq "Search Host Controller Service"}
Then You will see the list of servers that are running
Server : SPServer Name=WFE1 HostControllerURL : net.tcp://WFE1/ceres/hostcontroller/nettcp RepositoryVersion : 0 PrimaryHostController : True SearchServiceInstanceId : 43d4837c-b0c6-42e1-93ff-c8b872854be7
Server : SPServer Name=WFE2 HostControllerURL : net.tcp://WFE2/ceres/hostcontroller/nettcp RepositoryVersion : 0 PrimaryHostController : False SearchServiceInstanceId : 6d02e4ab-bfb9-442f-8a29-705274ec8262
Server : SPServer Name=WFE3 HostControllerURL : net.tcp://WFE3/ceres/hostcontroller/nettcp RepositoryVersion : 0 PrimaryHostController : False SearchServiceInstanceId : 98d9cc05-92d6-4e2a-b872-3bd7d22f33a4
I stopped and started it by running these two commands:
Stop-SPServiceInstance -Identity 98d9cc05-92d6-4e2a-b872-3bd7d22f33a4
Start-SPServiceInstance -Identity 98d9cc05-92d6-4e2a-b872-3bd7d22f33a4
Hopefully its work for you as well.