We can't connect you. HTTP 404

Michael Speights 20

I am receiving this error [see image below] on all my office 365 desktop applications. I can still access O365 applications via web browsers. I have uninstalled and reinstalled M365 Apps for enterprise several times with the error persisting. This error seems to occur randomly - While using Outlook I'll see that I'm not receiving new emails and be prompted to sign in since I'm not connected to exchange servers. After clicking 'password required' the company which we obtain our O365 license appears. I enter my credentials and then the error appears. Any suggestions?

We cant connect you

3 answers

adamr-nxnet 50 Reputation points

2023-10-26T12:57:11.3366667+00:00

Hi Michael,

Go to Control Panel > Internet Options > Connections > LAN settings > check Automatically detect settings and click OK
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10 people found this answer helpful.
dbrandenburg 0 Reputation points

2023-10-26T19:57:50.5266667+00:00

Nice! this worked for me. I was getting the noted error from Power BI Desktop.

Rajesh Kumar Singh 0 Reputation points

2023-11-03T09:55:04.8833333+00:00

This fixed the issue.

Abubakar Dar 5 Reputation points

2024-01-08T10:29:38.05+00:00

Thank you good Sir! I've been stuck at this problem for 2 days and nothing microsoft related was working on my laptop. THANKS A LOT. I wish i could send you money but I aint rich so you can just have my gratitute.

Matthew Williams 0 Reputation points

2024-01-18T10:41:00.16+00:00

where do I find the control panel? Is this on any microsoft app? Thanks

Abubakar Dar 5 Reputation points

2024-01-18T10:47:37.8466667+00:00

Press windows key and search "Control Panel" or just click on windows search and type it.

Matthew Williams 0 Reputation points

2024-01-18T10:50:13.0866667+00:00

Ok thank you I tried this but it seems this is not my issue

Tushar Pradeep Ingale 0 Reputation points

2024-07-21T15:31:25.9033333+00:00

This worked for me. I was getting an error from Microsoft Teams and Store.

Alexander Klement 0 Reputation points

2024-11-01T15:28:20.74+00:00

I was stuck there for 6 months now. I tried everything, your solution did the trick!!
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Olmo Rauba 10 Reputation points

2023-07-03T11:24:33.2666667+00:00

I have the same problem trying to log in to Teams or Power BI Desktop
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1 person found this answer helpful.
Michael Speights 20 Reputation points

2023-07-03T13:08:09.5233333+00:00

Have you gained access yet? It happened to me this morning as well. It might still be a local issue. Some users in my tenant are not reporting this issue.

Olmo Rauba 10 Reputation points

2023-07-03T16:42:42.5733333+00:00

It started working again around 3 PM.

Olmo Rauba 10 Reputation points

2023-07-10T09:22:16.23+00:00

The problem is back.

Any idea what might be causing it?

Michael Speights 20 Reputation points

2023-07-10T11:46:12.52+00:00

7:42 EST and the issue has reappeared for me as well. I am starting to think this is a backend issue. I already did the registry change suggested below.

Olmo Rauba 10 Reputation points

2023-07-10T18:07:37.3666667+00:00

I tried on a different machine, there it's working smoothly.

Must be some kind caching of credentials conflict.
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Konstantinos Passadis 19,171 Reputation points MVP

2023-07-03T16:46:13.18+00:00

Hello @Michael Speights !

A similar thread had the issue resolved

The problem was solved by configuring the following registry keys:

HKEY_CURRENT_USER\SOFTWARE\Microsoft\Office\16.0\Common\Identity]

"EnableADAL"=dword:00000000

"DisableADALatopWAMOverride"=dword:00000001

"DisableAADWAM"=dword:00000001

LINK : https://answers.microsoft.com/en-us/outlook_com/forum/all/fix-error-connecting-outlook-to-m365-http-404/bef8d6c5-a5c4-498b-ac72-bc81defb8256

I hope this helps!

Kindly mark the answer as Accepted and Upvote in case it helped!

Regards
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1 person found this answer helpful.
Michael Speights 20 Reputation points

2023-07-03T19:17:45.2466667+00:00

Hello Konstantinos,

I added the following DWORD 32 values to the registry location [HKEY_CURRENT_USER\SOFTWARE\Microsoft\Office\16.0\Common\Identity] and I still am not able to access my outlook.

Konstantinos Passadis 19,171 Reputation points MVP

2023-07-03T19:30:27.68+00:00

Hello @Michael Speights !

I restart is required , have you done it ?

Michael Speights 20 Reputation points

2023-07-03T19:41:31.7433333+00:00

Yes I have done a restart.There difference is login is showing - but when I put in the right credentials it doesn't connect me to the exchange servers.

Konstantinos Passadis 19,171 Reputation points MVP

2023-07-03T23:28:20.6033333+00:00

Hello @Michael Speights !

I supose we are talking about Outlook 2016

So kindly hav a look below

Did anything changed since the issue occured ?

Outlook 2016

Modern Authentication is enabled by default.

It is recommended that users force Outlook to use Modern Authentication by setting the DWORD value of the following registry key to 1:

HKEY_CURRENT_USER\Software\Microsoft\Exchange\AlwaysUseMSOAuthForAutoDiscover

For more information, see Outlook prompts for password and doesn't use Modern Authentication to connect to Microsoft 365.

MAPI/HTTP cannot be disabled. For more information, see Outlook 2010, 2013, 2016, or Outlook for Microsoft 365 doesn't connect Exchange using MAPI over HTTP as expected.

I hope this helps!

Kindly mark the answer as Accepted and Upvote in case it helped!

Regards
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We can't connect you. HTTP 404

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