Error: "Not able to connect to search service to retrieve valid settings"

I tried to change the query of the search results webpart and I've got this:

Fix is to use the SharePoint management Shell and define your account as an SSA Admin.


Here's the code to add yourself as SSA admin:
$principal = New-SPClaimsPrincipal "<domain>\<user>" -IdentityType WindowsSamAccountName

$spapp = Get-SPEnterpriseSearchServiceApplication

$security = Get-SPServiceApplicationSecurity $spapp –Admin

Grant-SPObjectSecurity $security $principal "Full Control"

Set-SPServiceApplicationSecurity $spapp $security –Admin