@Itch Sun-MSFT
I created a new permission level copying the "Contribute" permission level. Removed the options which will allow users to delete the content when they have "contribute" permission. I granted test account , the new permission level, it worked fine. the results appeared. However my client doesn't want end-users granted "Contribute" permission to the search page. They want search to work with "Read" permission (which was working fine before).Recently we applied the April 2020 security patch to the SP 2016 env.
The search page just gave me a correlation id. Based on the correlation id, i see the below in the ULS log.
The security validation for this page is invalid. Click Back in your Web browser, refresh the page, and try your operation again.
I tried using the developer tools and was able to track the below error.
403 forbidden error for the below REQUEST URL
Request Method: POST
https://Sitecollection/_vti_bin/client.svc/ProcessQuery