Outlook attempt to log on to Microsoft Exchange has failed.

One of the shared mailboxes in my customer organization has stopped allowing new Outlook connections.  The organization uses a local Exchange 2013 server.  The mailbox is called *** Email address is removed for privacy ***, and several users open the mailbox in Outlook, both 2010 and 2016.  It has been working fine until 2 days ago when it showed up as disconnected in one user.  Nothing I did allowed it to connect, and when I tried to remove the mailbox and re-add it, the process failed.  I also can no longer configure the mailbox in Outlook on any other machine - I've tried a mix of Windows 7 and 10, Outlook 2010 and 2016.  I logged into 2 unused computers, one of them a brand new Windows 10 box, as the actual verify user, and still can't load the mailbox.  The error I get in Outlook 2016 is:

  • Cannot start Microsoft Outlook. Cannot open the Outlook window. The set of folders cannot be opened. The attempt to log on to Microsoft Exchange has failed.

If I try to create a profile to the mailbox in Outlook 2010, the error is:

  • The action cannot be completed. The connection to Microsoft Exchange is unavailable. Outlook must be online or connected to complete this action.

I've tried a lot of the standard steps I see in other articles, like safe mode and resetnavpane, but those didn't help - not unexpected since this is a problem on multiple different machines and versions of Outlook.  Of particular note are two things:

  • All the other users that have this mailbox configured in Outlook have not experienced a problem - the mailbox is still connected and receiving mail.
  • I can log into the mailbox with no problem using OWA

The other night I rebooted the domain controller.  This seemed to fix the problem - but only for a few hours.  I was able to create an Outlook profile that night, and the affected user was connected, but by the next morning it was failing again, and the user was disconnected.  Last night I rebooted the Exchange server to similar results - it worked last night, but once again this morning I cannot create a new profile for that mailbox.

So I'm at a loss.  None of the standard suggestions seem to work - does anyone recognize this problem?

Update 09/16/19: I thought I had fixed the problem on Friday night by adding more space to the database drive - that drive was a little under 10% free, so I got it above that.  I tried adding the mailbox to my test machine and was successful, I then tested the machine showing as disconnected and it connected fine.  I tested all weekend, and finally on Sunday afternoon I successfully added the mailbox to another client.  It all seemed to work fine.  However, it's now Monday morning, and I went back to my test machine - it's failing again, with all the same errors as above.

This doesn't make sense - how could it work all weekend, but start failing Monday morning? The only correlation I see is the users coming in and working in Outlook.  I had everyone close Outlook over the weekend, now everyone will have it running - is it possible one of the existing Outlook clients could be causing this behavior somehow?


Hi Chris,


We may be looking at a setting that needs to be changed. It doesn't necessarily mean that there is an issue that needs to be resolved because as you said the issue is on and off. Because you're using an exchange server, this concern should be posted to the Technet Community forum, where IT experts and professionals are the common audiences and they can provide the best advice for this.


If you have other concerns, let us know.


Bob

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Thanks Bob, I'm working a possible angle now that I found on another thread.  It's for Exchange 2016, but I'm testing it out.  If it works I'll post back for posterity, otherwise I'll move this over to the TechNet forum.

Chris

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Hey, just wanted to post back in case anyone comes across this and needs a solution.  I don't have positive confirmation yet, but it's been a solid couple weeks and to date I haven't seen the issue recur.  Here's some information I posted in my TechNet thread that details what I did to address the issue:

I started noticing too much variation in who was being affected - sometimes a user would be affected, only for it to start working for them the next day, at which point another user would complain.  On my test machine, the mailbox worked fine all last weekend, then started failing on Monday morning when everyone came back into the office. It's starting to seem like there's some kind of connection limit.  So I came across some information on throttling policy and RcaMaxConcurrency, and setting that above the default limit of 40. I created a new policy, setting the value to 100 and applying it to the verify mailbox; now I'm waiting to hear back from the users. I'll report back with my results.

Here are links to the threads I found pointing me in this direction; wish me luck!

https://social.technet.microsoft.com/Forums/en-US/ebd52ddf-aeae-4d5d-aed4-f75d4f11a026/cannot-start-microsoft-outlook-the-attempt-to-log-on-to-microsoft-exchange-has-failed?forum=exchange2010

https://social.technet.microsoft.com/Forums/exchange/en-US/9198fe26-cf22-45b0-bdf7-36a80241600f/rcamaxconcurrency-throttling-question?forum=exchange2010

As I said above, since changing this value I haven't had any reports of the problems, so I'm pretty confident this is the solution.  Hope it helps someone in the future.

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Last updated December 3, 2020 Views 39,819 Applies to: