i am facing a problem on server. i have a page with post name contractors, it’s show an empty page with error message below

when i rename its permalink it will start working. but need the post name contractors in the page url. Secondly the page start working when i change the permalink setting to plain or add custom setting

/index.php/%postname%/

i create new page with that same permalink but it is showing the same issue. Right now i want to use Post name permalink setting. Can any help me in this scenario? i shall be thankful.