All Exception handler on Preparation is not working for specific users

I have a work flow type solution (web application), user initiate a request and click next button. On Second page loadingevent (i.e. Preparation), process verified some logic which is in a separate module (that means UI and CS modules).

If any logic or rule is failed then from CS, user exception is raised and UI page preparation method has exception handler for All Exceptions.

In this handler, we are showing message to user as is. It was working fine for all users but from few days, we start facing issues that for some users, instead of handling it in page exception handler, process is re-directed to common central handler which just show that Service unavailable, please go back and re-try. 

Any idea that what could be the reason of this strange behavior.

"Service unavailable" usually means there's something wrong with your infrastructure, like excessive loading times or IIS that's too busy or whatnot. It has likely nothing to do with specific users or specific applications.


"Service Unavailable" is hard coded value on that page

And as i said that logic is working for one user and same data, same detail, is not working and bringing user to this page.

Did you check the error log to see what the real error was?

Kilian Hekhuis wrote:

Did you check the error log to see what the real error was?

Yes,Kilian, i checked and it is same message which is really needed.

For example: Let suppose, i am passing Date of Birth to CS method which is checking that customer age should be 18+ else it will raise exception that age is less than 18.

So exception will be caught at UI and display the message.

Now for one user (same data), it catch exception in UI page and display message and for other user (same data), page exception handler is not executed and it reaches to this common page. and I checked backend service center and there same message is logged that age is less than 18 and not other message.

Kilian Hekhuis wrote:

Did you check the error log to see what the real error was?

I just observed that there is another exception just after my code error message stating

"Error closing the transaction to the database"

Will it be an issue, if yes then why it is happening for some specific users only?

Mean At same moment, for one user, it is working fine and same data but another user, it is not working where as few days ago, it was working for all.