Outlook webmail frozen in the light version and unresponsive

Question

Outlook webmail frozen in the light version and unresponsive

Aneesh 0

A week or so ago I switched my outlook webmail version (in Options > Outlook version) to "light mode". I would like to switch back to normal mode now. However, whenever I log onto my webmail, very few things that I click on are responsive. I cannot open any emails by clicking on them. I can open up Options, but cannot open the Outlook version tab to switch back to normal mode.

I have tried using Chrome, Edge, and Firefox. No luck. I tried clearing cache. No change.

When I try logging in via https://outlook.live.com/mail/0/ (as was suggested in a previous post here) I receive a "something went wrong" message with the following:

UTC Date: 2026-07-02T08:32:05.092Z
Client Id: 
Session Id: 
Client Version: 20260619010.12
BootResult: configuration
Back Filled Errors: Unhandled Rejection: Error: 500:undefined|undefined:undefined
err: Microsoft.Exchange.Clients.Owa2.Server.Core.OwaUserHasNoMailboxAndNoLicenseAssignedException
esrc: StartupData
et: ServerError
estack: Error: 500
    at Object.w [as createStatusErrorMessage]
    at 
st: 500
ehk: X-OWA-Error
efe: 
ewsver: 15.21.181.9
reqid: 
cv:

I am using Windows 11. This is my work email and so would appreciate any assistance on getting it back to normal. Up to now I have been forced to use the outlook app on my phone in place of the webmail option.

Thank you,

Aneesh

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1 answer

Your answer

Answer 1

Demi-N 18,735 Microsoft External Staff Moderator

Hello @Aneesh,

Thank you for your detailed description and for sharing the error information.

To better understand your environment and provide the most appropriate guidance, I would like to clarify a few details first.

Could you please let me know which email address you are using? You do not need to post the full address publicly, just the domain portion would be helpful (for example: @outlook.com, @hotmail.com, @company.com, etc.).

I would also like to know whether you encounter the same issue when signing in through: https://outlook.office.com

If you do see a similar error there, could you please share a screenshot of the full error message (with any personal or sensitive information masked before posting)?

Additionally, do you know which Microsoft product or subscription your account is associated with? For example: Microsoft 365 Business Basic, Microsoft 365 Business Standard,...

If you're unsure which subscription is associated with the account, could you please try accessing the following page and let me know whether you're able to sign in successfully: https://portal.office.com/account/?ref=Harmony

If the page opens correctly, please navigate to the "Subscriptions" section and share a screenshot similar to the example below. This will help me understand what Microsoft product or license is assigned to the account. Please remember to hide any personal or sensitive information before uploading the screenshot.

User's image

If you're unable to access the page or encounter an error, please let me know and share a screenshot of what you see, as that information may also help narrow down the cause of the issue.

At this stage, I'd like to gather a little more information before suggesting further troubleshooting, as the error could be related to the mailbox type, licensing, or the service associated with the account. The details above will help me better understand the scenario and guide you in the right direction.

Thank you for your cooperation, and I look forward to your reply.

Best regards,

Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.

Aneesh 0

Thanks for the reply.

The email domain is @slu.se

When signing in through: https://outlook.office.com I get this error message (I masked/deleted some lines as above).

UTC Date: 2026-07-02T09:30:12.722Z

Client Id: 
Session Id: 
Client Version: 20260619010.12
BootResult: configuration
Back Filled Errors: Unhandled Rejection: Error: 500:undefined|undefined:undefined
err: Microsoft.Exchange.Clients.Owa2.Server.Core.OwaUserHasNoMailboxAndNoLicenseAssignedException
esrc: StartupData
et: ServerError
estack: Error: 500
    at Object.w [as createStatusErrorMessage]
    at 
st: 500
ehk: X-OWA-Error
efe: 
ewsver: 15.21.181.9
reqid: 
cv:

Here are the licences that I see when navigating through the link you gave me above.

User's image

Thank you very much,

Aneesh

Demi-N 18,735 Reputation points Microsoft External Staff Moderator

2026-07-02T10:22:17.2866667+00:00
Hi @Aneesh,

Thank you for your information and screenshots, they were very helpful.

Based on the screenshots you provided, it appears that your account is currently missing an Exchange Online license, which explains the error message: "UserHasNoMailboxAndNoLicenseAssignedException"

As indicated by the error, the system is unable to find an Exchange mailbox associated with your account because an Exchange Online license is not currently assigned.

Since your account is managed by your school, the best way to resolve this would be to contact your school's IT administrator and ask them to review the license assignment for your account.

They can verify this by following these steps:

Sign in to https://admin.microsoft.com/ using an administrator account.

Go to Users > Active users.

Select your user account.

Choose Licenses and apps.

Expand Apps.

Verify that "Exchange Online (Plan 1 or Plan 2)" is enabled.

If an Exchange Online license is already assigned, they may also try temporarily removing the license, saving the changes, and then reassigning it. After that, they should allow some time for the changes to synchronize and then check whether the issue has been resolved.

If you are unsure who your IT administrator is, you can refer to the following Microsoft article for assistance: How do I find my Microsoft 365 admin? | Microsoft Support

I hope this helps clarify the cause of the issue. Please feel free to keep me updated on the outcome, and I'll be happy to assist further if needed.

Best regards,
Aneesh 0 Reputation points

2026-07-02T11:29:16.11+00:00

Thank you very much. I will contact my institutes IT administrator and get back to you if there are any issues.
Demi-N 18,735 Reputation points Microsoft External Staff Moderator

2026-07-02T13:13:34.9266667+00:00

Hi @Aneesh,

Thank you for your reply. Please feel free to work with your IT administrator, and if you encounter any issues or have any further questions, don't hesitate to come back and let me know. I'll be happy to help where I can.