Some times all of a sudden portal applications give a common ‘page cannot be displayed error’. It happens consistently/ inconstantly based on the degree of the problem.
The following screenshots are a compilation of intermittent errors thrown while accessing the portal through a reverse-proxy URL, even the errors from the Web-dispatcher could be same.
Where the error is, in Portal or in the Reverse Proxy: The error scenario has to be reproduced to get to the root cause of this error. As part of the troubleshoot, try reproducing the scenario from the Reverse-proxy URL and the same using a Web-Dispatcher URL. The results here can be classified as below
1. There is an error only when the application is accessed through Reverse Proxy: This means that there is some problem with the Reverse-proxy server or with the Firewall that is between the Internet and proxy server.
1.1 Check the data transferred in and out of the reverse-proxy: A standard packet capturing tool can also be used. If the data packets transfer is not tallying, then there is a problem with the proxy server output. The proxy server needs to be examined.
1.2 Activate the ‘Network Traces’: Using a network trace tool like NETMON or Ethereal, you should be able to verify if the server is abruptly closing the TCP connection. As to why the server would abruptly close the TCP connection, you would need to debug the server application. The firewall could be the problem at times.
1.3 HTTP Watch Tool: You can also use the HTTP Watch Tool to capture the exact error. In our case we had the following errors logged in with the reverse-proxy URL
You can download http watch software from below link [http://www.download.com/HttpWatch-Basic-Edition/3000-12775_4-10078399.html]
Enable this on Browser and record while browsing portal from
a) Web-dispatcher URL
b) reverse- proxy URL
You can observe this error in the http watch log, which will be easier to troubleshoot the HTTP errors.
2. The error comes up with both the URLs: This means that the Backend application is not accessible to portal due to network connectivity issue (between portal and the backend) (assuming that the system object/ Java Connectors are configured correctly).
2.1 Check if the Backend/source system is down: If the Backend system is down then this error is quite common in the BSP/ITS based iViews else,
2.2 Check if the application is working other wise: If the application is working in the Backend, then the issue can be narrowed down as a firewall/network connectivity that is affecting the portal communication with its backend.
2.3 If the application is not working in the Backend: When there is problem with the Backend application, then there is a message (dump) shown in the containing portal iView.
Please add up if you know any other alternative to troubleshoot this error.