Hi @girik06  If this is customization issue you may get issues on the customized screens but not the site level.

• Have you published brand new other local instance and verified? Just to check whether this issue causing from customization or not? 
• Restarted server and verified in sandbox?

Hi Naveen.
In Local Instance, Everything is working fine with Sandbox Snapshot.
Restarted  and checked still Server Instance is not opening.
Any other way to check this error
Thanks.

Hi @girik06  Not sure and never faced this issue.

I’m assuming this is not an issue with the customization and it is more of configuration kind of issue.

here is the link for your reference.

https://stackoverflow.com/questions/13020103/webapis-messagean-error-has-occurred-on-iis7-not-in-iis-express