Exchange 2016 ecp connection issue

Hi Guys,

I am desperate for a solution!

We've setup an Exchange server 2016, transferred all the mailboxes across from Exch 2010 and everything was working just fine.
Abruptly the server could not access OWA or ECP and gave an error:

Bad Request - Invalid hostname
HTTP Error 400.  The request hostname is invalid.

Workstations were also unable to connect.

Upon troubleshooting I found all certificates on the server to be missing.
Creating a new request for both Godaddy and Selfsigned produced blank entries after import.

I recreated virtual directories, confirming virtual URL's, etc to no avail.
I called it a day, as we were under a lot of pressure and reloaded Exchange 2016 in a VM.

This time round I documented every step and followed the setup conservatively.
Fortunately the mailboxes were still available in the "broken" setup to be transferred.  This made me believe that the initial errors were IIS related.

The second-installation 2016 VM server (ecp, OWA, mapi) all was working fine and all mailboxes were transferred yesterday.

I made an IIS backup today "appcmd add backup xxx" to prevent an unrecoverable scenario as with the first 2016 installation.

About 30 minutes after the backup, ECP was broken yet Again!
BAD REQUEST - Invalid Hostname
HTTP Error 400.  The request hostname is invalid.

Needless to say did a couple of checks in EMC, including Default Website bindings in IIS, and did not find anything wrong ...

Upon trying for about 30 minutes ecp was abruptly accessible!  (Without me doing anything)

I am not sure what is causing the "unstable" behaviour, but we in dire need of a fully operational server.

I noticed there are quite a few articles on this specific error.  

Perhaps anyone came across this as well?

We cannot afford having the server to go down on us again - without reason!

Anyone running 2016 successfully, without encountering this specific issue?
Will appreciate any assistance ..

I checked the certificates and Fortunately they are still listed in EMS (previous installation was all blank)
Rupert EghardtProgrammerAsked:
Who is Participating?

[Product update] Infrastructure Analysis Tool is now available with Business Accounts.Learn More

I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

Jose Gabriel Ortega CastroCEO Faru Bonon IT - EE Solution ExpertCommented:
The 1st thing to check is the services on the new exchange server.
2nd thing to check is the SCP that can be checked using:
3rd are Certificates

Did you check all of that?
do you see event viewers for error?
Valentina PerezExchange ServersCommented:
Hi Rupert,

This error you receive internally or externally?

Exchange 2010 are still in use? All mailboxes were if you shutdown Exchange 2010...Exchange 2016 works?

Rupert EghardtProgrammerAuthor Commented:
Thanks for the recommendations guys,

Our Exchange 2010 is still running.  Some low level mailboxes are still on Exchange 2010 and need to be transferred.
Thus the server is still on, but DNS references to the new Exchange server for OWA, ECP, AutoDiscover, etc.

With our first installation of Exchange 2016, the issue with ECP was internal and external and we had to use EMS to configure certificates, as EMC was completely down.

As mentioned, our real challenge was that we could not install certificates, as everything was imported blank, thus resulting in all services being down as a result.

Fortunately the second 2016 installation retained the certificates thus far and "http 400 error" seems to have been limited to Chrome, where IE seem to work.

So far our second Exchange 2016 has been behaving.

One small issue:

AutoDiscover.xml externally gives the logon prompt, which is correct.
Phones however does not lookup AutoDiscover automatically when adding new mail accounts.
Marshal HubsEmail ConsultantCommented:
@Rupert Eghardt
"Our Exchange 2010 is still running.  Some low level mailboxes are still on Exchange 2010 and need to be transferred."

You can easily migrate mailboxes from Exchange 2010 to Exchange 2016 by using Stellar EDB to PST Converter. For more information, please check this link:


Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today

From novice to tech pro — start learning today.