Operation links doesn't show up

Have you tried repairing Webform’s configuration?

Nope

Just repaired configuration, but no success.

Try clearing the cache. What version did you upgrade from?

cache has been cleared but no success, don't remember, but it was minor version, after updation, database updation was done.

The site has thrown an error: Missing filter plugin: filter_null. when tried to load "/admin/structure/webform/config/advanced" that might have casued the issue.

You may need to re-save your text formats. Search for "filter_null drupal" for details.

The "filter_null" issue is resolved now by making changes into the yml file of the filter. but still the issue persists. Also, it seems to me the issue is related to permission as accessing any form "build" through url lead to You are not authorized to access this page.

Also, creating a new webfrom lead to "Access Denied". see the attached screenshot.

I fixed the issue. it was related the some custom permission used by another module.

Automatically closed - issue fixed for 2 weeks with no activity.