Problem: While trying to add a new user to a SharePoint group, SharePoint 2013 People Picker displayed the error: “Sorry, we’re having trouble reaching the server.”
- The server may not have enough resources such as Memory to process the function without timing out. Try adding more memory to your SharePoint 2013 web front end server.
- If the “HTTP Activation” feature is not enabled, You may face this issue. Log in to your WFE >> Go to Server Manager >> Add Roles and Features >> Select HTTP Activation and install.
- Try IIS reset once from all front end servers.
- Check Alternate Access Mappings settings for the web application.
- Try deactivating the “Limited-access user permission lockdown mode” Feature from site collection features (This worked in one of the external facing sites).
- Make sure the domain account you are using for a SharePoint service account has the necessary permissions to read domain accounts, If you have one-way trust domain – Set the app password (stsadm -o setapppassword -password “Password”) and follow the KB to add people picker domain https://support.microsoft.com/en-us/kb/2874332
- Check if Anonymous Authentication is enabled for your web site in IIS.
- Try updating “Query timeout” value from 25 to 60! (under: 15\TEMPLATE\LAYOUTS\clientpeoplepicker.js >> SPClientPeoplePicker.UserQueryMaxTimeout)
- Try extending the web application to new port!