In our role as Server Administrators for website owners, server owners and hosting companies, we perform a wide range of tasks, from hack recovery to resolving server errors.
Recently we were contacted by a Microsoft Exchange server owner, who was getting blank page in OWA. OWA is the Outlook Web Access for Microsoft Exchange users to view their emails.
The blank page was noticed in Google chrome and latest browser versions, after successful authentication in the login page. Today, we’ll see what causes this issue and how to resolve it.
Why Exchange OWA gives blank page after login
Website attacks are done in many ways, from code injections to website redirection. Secure browsing is a security measure adopted by latest browsers to avoid attacks to websites.
Secure access to sites is ensured using SSL certificates to verify the authenticity of the web server you are connected to. But some attackers try to fool the browser with a certificate and then redirect to a different malicious web site.
To prevent such attacks, most web browsers incorporate a further check. For instance, Google Chrome compares the SSL information provided by the site with the web server to which connection is made.
If the details do not sync, the connection will not work fine. Since all websites are not secure by default, this feature of Chrome gradually forces the web to move towards a secure HTTPS.
In the case of Microsoft OWA issue that was reported by the customer, the login page was loading fine, but was giving a blank page when user successfully login to it.
The same page worked fine in some older browser versions. This clearly showed that the issue was related to the browser security features incorporated recently.
What causes Exchange OWA blank page after login
In Microsoft Exchange server, the SSL misconfiguration in the server can lead to the OWA page showing blank page in latest browsers such as Google Chrome.
IIS server secures websites using SSL bindings. The SSL certificate is bound to the HTTPS port 443 of the website. If there are any configuration mistakes in this setting, it can cause issues when the site is accessed.
When an Exchange server is installed as a Client Access Role or Mailbox Role, there will be two websites in IIS – The Default Web Site and the Exchange Back End, both accessed via HTTPS by default.
Both these sites in IIS have separate SSL bindings allotted to them. The following issues related to SSL bindings, can lead to Exchange OWA blank page after login.
1. Configuration issues in SSL binding for Exchange site
The SSL bindings of Exchange default site and Exchange backend should sync and should be the same certificate. If not, the OWA can show blank page after login.
If the SSL binding contains incorrect information, or if the certificate hash of the binding is different from that of other bindings for the default application ID, OWA fails to function properly.
2. SSL certificate for the Exchange site missing
It can happen that the website that runs the ‘Exchange Backend’ loses the certificate for its https binding somehow, or the certificate gets expired.
When the Exchange Back End site in IIS of the Exchange server is no longer bound to a certificate, OWA will give blank page, as the SSL certificate is “Not Selected”.
3. Incorrect time settings in server clock
While SSL issues are the main cause for OWA giving blank page in latest browsers, at times the clock sync issues can also lead to similar issues.
This time sync issue can occur if the Exchange server’s system clock is ahead or behind from what it should be, causing OWA to load with blank page.
4. Exchange components or license issues
Exchange server has server modules and pre-requisites related to it, for it to function right. If any of these pre-requisites is missing or not functioning right, OWA blank page can show.
License issues can also lead to OWA problems. Exchange server maybe running with trial (Evaluation) license, or the “Exchange Product Key” can be incorrect.
How to resolve Exchange OWA blank page after login
To resolve the Exchange OWA blank page issue, we first diagnose the cause, by performing a 360 degree check that involves SSL configuration to Exchange settings.
If the SSL certificate binding is incorrect, we resolve it by changing the binding settings in IIS for the two websites of Exchange, for the HTTPS port (443 for default site and 444 for backend).
The SSL certificate corresponding to the two sites are confirmed to be the same and valid one. After restarting the related services, OWA would start loading fine properly.
In the server that we got to handle, this alone did not fix the issue. There were some pre-requisites missing for the Exchange ‘Server Manager’ module, which was causing OWA to show blank page.
We launched the Exchange Management Shell and added the missing features into the module. After reloading the TCP port sharing service, the OWA loaded fine.
Conclusion
OWA is a commonly used interface by Exchange users. Here, we saw the various reasons that can cause OWA showing blank page after login, and how it can be fixed by our systematic debugging method.
Spot on! Correcting the Exchange Back End certificate binding fixed this issue for me after the August Exchange 2013 security updates broke it.