Hello,

I have an odd situation where we are preparing 2 exchange 2013 servers to migrate 2010 servers to 

so currently:

2x Exchange 2010 (with dag)

2x Exchange 2013 (with dag).

Now it's behaving extremely odd when it comes to ECP for the 2013 servers.

randomly it works and doesn't work.

i generally try it from localhost on both 2013 servers, and individual server ip's from lets say 4 or 5 places.

all same login, and admin user is inside mailbox db DAG cluster.

now the problem:

it randomly pops up auth.owa error 500 

when i say random i truly mean random, sometimes everything 100% works, i am able to login 100% from all servers.

then i check back lets say 2 hours later.. some obtain auth.owa errors while others work.

What i tried:

- I rebuild OWA (first with reset, then with remove and re-add method) on both 2013 servers.

- removed killbit file from 2013's

- rebuild exchange 2013's (just exchange it self).

- checked heartbeat monitor boxes and removed the null values.

----------------------------------

It's safe to say i am kind of lost on what to try next. 

i am also mistefied why it randomly works, i know it's internally loadbalanced, but shutting down 1 of the 2013 servers did not get rid of this strange behavior.

is it possible that the exchange 2010 servers play a part in this issue?

Any ideas, any help is very much welcome!.

Regards,

Hello

please check eventlog on all 2013 exchange server and iis log for error.

Hi,

Please check whether the Microsoft Forms Based Authentication service is running on all Exchange servers. 

Similar thread for your reference: https://social.technet.microsoft.com/Forums/exchange/en-US/8cf6886f-a96f-44f1-88ee-bd3a42349fa9/owa-brings-up-logon-screen-but-after-login-gives-http-500-internal-server-error

Also check the authentication configuration on CAS.

Get-OwaVirtualDirectory -Server <server name> | fl *auth*

Set-OwaVirtualDirectory -Identity " server name \owa (Default Web Site)" -FormsAuthentication $true

Thanks

Hello,

To summ things up:

1) No it's not the forms auth service, they don't even exist in Exchange 2013's but only 2010 as far as i am aware.

2) Auth and websites where properly set, even removed, re-installed etc.

----------------------------------------

- After some more investigation it seemed it had nothing to do with OWA but everything to do with ECP. (normal OWA login did work, while ECP failed).

- Exchange 2010 proxy worked fine too

In this case after re-installing Exchange 2013's as mentioned in the original post --> we did forget 1 thing: Update after re-install.

After doing all of the above.. updating exchange 2013's solved the issue.

a common solution for an odd problem :-)

Regards,

Marco