Where can we find web api logs in cloud?

Follow the steps provided below:

Go to Sytem logs from Admin Comsole -> perf logs -> web_api_summary.csv / web_api_details.csv

Thanks for the response.

Exception message is not found in both the files. Where exactly can we look for error message?

Please look out the errors in tomcat-access.log file . we can identify all the errors in access log.

Here it just displays something like below

2020-01-21 06:08:02 /suite/webapi/persistData - 500 0.282

I wanted to check the exception message.

Can you provide more information about what issue you are having? The logs may not be the best place to look depending on the problem. Are you receiving an error message when you call the Web API? If yes, what error are you getting? Also, have you tried to execute the Web API from the Appian Designer? That can help you diagnose issues with the expression directly through the Web API designer.

Web API is working fine from Appian side and  i have also tested using rest client, everything seems to be fine. But when a third party tries to consume this, getting an error - 500 internal server error.

Now they need to know the exact error message to debug.

Have you checked the security of the webAPI and anything that might be consumed by the webAPI to ensure that access is granted for the third party ? 

Ok I think the Application Server log is the best thing to check out here. It's usually a catch all for many errors from different systems and can probably give you a good idea where to search. You can find the Application Server log by looking at the tomcat-stdOut.log for the date you need.