Users may have been unable to view contents of the Files tab in newly created channels in Microsoft Teams.
ID	Workload Feature	Title	Classification	Severity	Start Time	Last Updated
TM1074644	Microsoft Teams Teams Components Files	Users may be unable to view contents of the Files tab in newly created channels in Microsoft Teams	advisory		23-Apr-2025 03:00	24-May-2025 19:32
Update: 24-May-2025 19:31 Title: Users may be unable to view contents of the Files tab in newly created channels in Microsoft Teams User Impact: Users may have been unable to view contents of the Files tab in newly created channels in Microsoft Teams. More Info: Impact occurred in the Microsoft Teams desktop and web apps, and any file viewing requests reliant on the API leveraged for viewing files through Microsoft Teams may have failed. Final Status: After monitoring the progression of our secondary fix, we've confirmed that it's completed deploying and has successfully addressed the issue. Scope of Impact: Some users who attempted to view contents of the Files tab in newly created Microsoft Teams channels in the desktop client may have been impacted. Start Time: Wednesday, April 23, 2025, at 7:00 AM UTC End Time: Saturday, May 24, 2025, at 7:20 PM UTC Root Cause: A language configuration issue introduced by a recent change on the service side was resulting in impact to an API leveraged for serving files through Microsoft Teams. Next Steps: -We're investigating further into the impacting recent change so that we can get a clear understanding of how it introduced a language configuration issue along with learning how we didn't catch this impact prior to deployment. The results of this investigation will help prevent similar impact from occurring in the future. This is the final update for this event. Update: 24-May-2025 14:14 Title: Users may be unable to view contents of the Files tab in newly created channels in Microsoft Teams User Impact: Users may be unable to view contents of the Files tab in newly created channels in Microsoft Teams. More Info: Impact occurs in the Microsoft Teams desktop and web apps, and any file viewing requests reliant on the API leveraged for viewing files through Microsoft Teams may fail. Current Status: We're continuing to monitor the progression of the secondary fix as it nears completion. Based on current estimates, we suspect deployment will complete by our next scheduled update. Scope of Impact: Some users attempting to view contents of the Files tab in newly created Microsoft Teams channels in the desktop client may be impacted. Start Time: Wednesday, April 23, 2025, at 7:00 AM UTC Root Cause: A language configuration issue introduced by a recent change on the service side is resulting in impact to an API leveraged for serving files through Microsoft Teams. Next Update By: Sunday, May 25, 2025, at 1:00 AM UTC Update: 22-May-2025 22:19 Title: Users may be unable to view contents of the Files tab in newly created channels in Microsoft Teams User Impact: Users may be unable to view contents of the Files tab in newly created channels in Microsoft Teams. More Info: Impact occurs in the Microsoft Teams desktop and web apps, and any file viewing requests reliant on the API leveraged for viewing files through Microsoft Teams may fail. Current Status: Our secondary fix has been deploying as expected and is at 87 percent saturation. We're now finalizing our tertiary fix which we anticipate will be completed and subsequently deployed prior to our next scheduled update. Additionally, we aim to gather a remediation timeline once the aforementioned actions have taken place. Scope of Impact: Some users attempting to view contents of the Files tab in newly created Microsoft Teams channels in the desktop client may be impacted. Start Time: Wednesday, April 23, 2025, at 7:00 AM UTC Root Cause: A language configuration issue introduced by a recent change on the service side is resulting in impact to an API leveraged for serving files through Microsoft Teams. Next Update By: Saturday, May 24, 2025, at 10:00 PM UTC Update: 20-May-2025 20:32 Title: Users may be unable to view contents of the Files tab in newly created channels in Microsoft Teams User Impact: Users may be unable to view contents of the Files tab in newly created channels in Microsoft Teams. More Info: Impact occurs in the Microsoft Teams desktop and web apps, and any file viewing requests reliant on the API leveraged for viewing files through Microsoft Teams may fail. Current Status: We've validated that our secondary fix has been deploying as expected and is at 19 percent saturation. Some users may see impact alleviate as the fix progresses toward completion. Scope of Impact: Some users attempting to view contents of the Files tab in newly created Microsoft Teams channels in the desktop client may be impacted. Start Time: Wednesday, April 23, 2025, at 7:00 AM UTC Root Cause: A language configuration issue introduced by a recent change on the service side is resulting in impact to an API leveraged for serving files through Microsoft Teams. Next Update By: Friday, May 23, 2025, at 4:00 AM UTC Update: 20-May-2025 13:38 Title: Users may be unable to view contents of the Files tab in newly created channels in Microsoft Teams User Impact: Users may be unable to view contents of the Files tab in newly created channels in Microsoft Teams. More Info: Impact occurs in the Microsoft Teams desktop and web apps, and any file viewing requests reliant on the API leveraged for viewing files through Microsoft Teams may fail. Current Status: We've completed our internal validations of our secondary fix to ensure that its deployment addresses the language configuration issue without introducing any unexpected problems to the service. We've initiated deployment of our secondary fix which we anticipate will finish saturation by the end of day on Thursday, May 22, 2025. We aim to provide updates on our timeline to mitigation as the incident progresses towards resolution. Scope of Impact: Some users attempting to view contents of the Files tab in newly created Microsoft Teams channels in the desktop client may be impacted. Root Cause: A language configuration issue introduced by a recent change on the service side is resulting in impact to an API leveraged for serving files through Microsoft Teams. Next Update By: Wednesday, May 21, 2025, at 2:00 AM UTC Update: 19-May-2025 13:05 Title: Users may be unable to view contents of the Files tab in newly created channels in Microsoft Teams User Impact: Users may be unable to view contents of the Files tab in newly created channels in Microsoft Teams. More Info: Impact occurs in the Microsoft Teams desktop and web apps, and any file viewing requests reliant on the API leveraged for viewing files through Microsoft Teams may fail. Current Status: Our preventive fix has completed deployment and our testing with affected users has verified that it prevents additional users from experiencing the problem. In parallel, we're internally validating our secondary fix to ensure that its deployment addresses the language configuration issue without introducing any unexpected problems to the service, and we're expecting that an estimated timeline for its deployment and the remediation of impact will be available by our next scheduled update. Scope of Impact: Some users attempting to view contents of the Files tab in newly created Microsoft Teams channels in the desktop client may be impacted. Root Cause: A language configuration issue introduced by a recent change on the service side is resulting in impact to an API leveraged for serving files through Microsoft Teams. Next Update By: Tuesday, May 20, 2025, at 6:30 PM UTC Update: 17-May-2025 14:25 Title: Users may be unable to view contents of the Files tab in newly created Microsoft Teams channels in the desktop client User Impact: Users may be unable to view contents of the Files tab in newly created Microsoft Teams channels in the desktop client. More Info: Impact may also occur within Microsoft Teams on the web, and any file viewing requests reliant on the API leveraged for viewing files through Microsoft Teams may fail. Current Status: The preventive fix has been deployed and is progressing as expected. Deployment of the secondary fix is underway, and we're continuing to monitor both efforts to ensure full remediation. We'll provide a resolution timeline once it's available. Scope of Impact: Some users attempting to view contents of the Files tab in newly created Microsoft Teams channels in the desktop client may be impacted. Root Cause: A language configuration issue introduced by a recent change on the service side is resulting in impact to an API leveraged for serving files through Microsoft Teams. Next Update By: Monday, May 19, 2025, at 6:30 PM UTC Update: 17-May-2025 03:30 Title: Users may be unable to view contents of the Files tab in newly created Microsoft Teams channels in the desktop client User Impact: Users may be unable to view contents of the Files tab in newly created Microsoft Teams channels in the desktop client. More Info: Impact may also occur within Microsoft Teams on the web, and any file viewing requests reliant on the API leveraged for viewing files through Microsoft Teams may fail. Current Status: We've deployed the aforementioned preventive fix to the affected environments, and are continuing to monitor its progress. Additionally, we're at the final stages of validating our secondary fix to address currently broken sites for deployment and expect to provide deployment time line by our next scheduled update. Scope of Impact: Some users attempting to view contents of the Files tab in newly created Microsoft Teams channels in the desktop client may be impacted. Root Cause: A language configuration issue introduced by a recent change on the service side is resulting in impact to an API leveraged for serving files through Microsoft Teams. Next Update By: Saturday, May 17, 2025, at 8:00 PM UTC Update: 16-May-2025 23:29 Title: Users may be unable to view contents of the Files tab in newly created Microsoft Teams channels in the desktop client User Impact: Users may be unable to view contents of the Files tab in newly created Microsoft Teams channels in the desktop client. More Info: Impact may also occur within Microsoft Teams on the web, and any file viewing requests reliant on the API leveraged for viewing files through Microsoft Teams may fail. Current Status: We've tested and validated both our fixes and are deploying the preventive fix to the affected environments, which we anticipate may be completed by our next scheduled update. In parallel, we're preparing our secondary fix to address currently broken sites for deployment, which is taking longer than previously anticipated and is now expected to begin deploying by our next update. Scope of Impact: Some users attempting to view contents of the Files tab in newly created Microsoft Teams channels in the desktop client may be impacted. Root Cause: A language configuration issue introduced by a recent change on the service side is resulting in impact to an API leveraged for serving files through Microsoft Teams. Next Update By: Saturday, May 17, 2025, at 7:30 AM UTC Update: 16-May-2025 16:58 Title: Users may be unable to view contents of the Files tab in newly created Microsoft Teams channels in the desktop client User Impact: Users may be unable to view contents of the Files tab in newly created Microsoft Teams channels in the desktop client. More Info: Impact may also occur within Microsoft Teams on the web, and any file viewing requests reliant on the API leveraged for viewing files through Microsoft Teams may fail. Current Status: The testing and validation of our fixes is ongoing. We expect that our fix to address currently broken sites will begin deployment by our next scheduled update, at which time we also expect to have a timeline for the deployment of the fix to ensure newly created sites aren't impacted by this issue. Scope of Impact: Some users attempting to view contents of the Files tab in newly created Microsoft Teams channels in the desktop client may be impacted. Root Cause: A language configuration issue introduced by a recent change on the service side is resulting in impact to an API leveraged for serving files through Microsoft Teams. Next Update By: Saturday, May 17, 2025, at 4:00 AM UTC Update: 16-May-2025 15:13 Title: Users may be unable to view contents of the Files tab in newly created Microsoft Teams channels in the desktop client User Impact: Users may be unable to view contents of the Files tab in newly created Microsoft Teams channels in the desktop client. More Info: Impact may also occur within Microsoft Teams on the web, and any file viewing requests reliant on the API leveraged for viewing files through Microsoft Teams may fail. Current Status: We've completed the development of the fix to ensure newly created sites no longer see the issue, as well as the other to repair existing sites which are impacted. We're proceeding with our testing and validation of both fixes in our internal testing environment to confirm their efficacy. Scope of Impact: Some users attempting to view contents of the Files tab in newly created Microsoft Teams channels in the desktop client may be impacted. Root Cause: A language configuration issue introduced by a recent change on the service side is resulting in impact to an API leveraged for serving files through Microsoft Teams. Next Update By: Friday, May 16, 2025, at 9:30 PM UTC Update: 16-May-2025 13:20 Title: Users may be unable to view contents of the Files tab in newly created Microsoft Teams channels in the desktop client User Impact: Users may be unable to view contents of the Files tab in newly created Microsoft Teams channels in the desktop client. More Info: Impact may also occur within Microsoft Teams on the web, and any file viewing requests reliant on the API leveraged for viewing files through Microsoft Teams may fail. Current Status: After the test of our initial fix, we've confirmed that the issue impacts different types of site creation templates, indicating our fix is not comprehensive enough to resolve the entirety of impact. We're developing two additional fixes as a result; one of which will correct site creation templates so newly created sites aren't impacted by this issue and another to repair existing sites experiencing impact. Scope of Impact: Some users attempting to view contents of the Files tab in newly created Microsoft Teams channels in the desktop client may be impacted. Root Cause: A language configuration issue introduced by a recent change on the service side is resulting in impact to an API leveraged for serving files through Microsoft Teams. Next Update By: Friday, May 16, 2025, at 7:30 PM UTC Update: 16-May-2025 08:44 Title: Users may be unable to view contents of the Files tab in newly created Microsoft Teams channels in the desktop client User Impact: Users may be unable to view contents of the Files tab in newly created Microsoft Teams channels in the desktop client. More Info: Impact may also occur within Microsoft Teams on the web, and any file viewing requests reliant on the API leveraged for viewing files through Microsoft Teams may fail. Current Status: We're progressing with testing the fix with a subset of affected users. Once completed, we'll start the deployment to all affected environments. Scope of Impact: Some users attempting to view contents of the Files tab in newly created Microsoft Teams channels in the desktop client may be impacted. Root Cause: A language configuration issue introduced by a recent change on the service side is resulting in impact to an API leveraged for serving files through Microsoft Teams. Next Update By: Friday, May 16, 2025, at 5:30 PM UTC Update: 16-May-2025 04:05 Title: Users may be unable to view contents of the Files tab in newly created Microsoft Teams channels in the desktop client User Impact: Users may be unable to view contents of the Files tab in newly created Microsoft Teams channels in the desktop client. More Info: Impact may also occur within Microsoft Teams on the web, and any file viewing requests reliant on the API leveraged for viewing files through Microsoft Teams may fail. Current Status: We're continuing the final testing of our fix with a subset of affected users. Once complete we'll begin deploying the fix to the remainder of the affected environment. Scope of Impact: Some users attempting to view contents of the Files tab in newly created Microsoft Teams channels in the desktop client may be impacted. Root Cause: A language configuration issue introduced by a recent change on the service side is resulting in impact to an API leveraged for serving files through Microsoft Teams. Next Update By: Friday, May 16, 2025, at 3:00 PM UTC Update: 16-May-2025 01:28 Title: Users may be unable to view contents of the Files tab in newly created Microsoft Teams channels in the desktop client User Impact: Users may be unable to view contents of the Files tab in newly created Microsoft Teams channels in the desktop client. More Info: Impact may also occur within Microsoft Teams on the web, and any file viewing requests reliant on the API leveraged for viewing files through Microsoft Teams may fail. Current Status: We're finalizing the testing of our fix with a subset of affected users prior to its full deployment. We're aiming to complete our testing by our next scheduled update, at which point we'll move ahead to begin deploying the fix throughout the remainder of the affected environment. Scope of Impact: Some users attempting to view contents of the Files tab in newly created Microsoft Teams channels in the desktop client may be impacted. Root Cause: A language configuration issue introduced by a recent change on the service side is resulting in impact to an API leveraged for serving files through Microsoft Teams. Next Update By: Friday, May 16, 2025, at 8:30 AM UTC Update: 16-May-2025 00:11 Title: Users may be unable to view contents of the Files tab in newly created Microsoft Teams channels in the desktop client User Impact: Users may be unable to view contents of the Files tab in newly created Microsoft Teams channels in the desktop client. More Info: Impact may also occur within Microsoft Teams on the web, and any file viewing requests reliant on the API leveraged for viewing files through Microsoft Teams may fail. Current Status: We've completed the internal validation of our expedited fix for the issue to prevent any further newly created channels from becoming impacted and are now working to test the fix with a subset of affected users before deploying it throughout the rest of the impacted environment. Additionally, we've identified that some users are reporting that impact still occurs within the Microsoft Teams web client, and our latest understanding of the underlying root cause indicates that any file viewing requests reliant on the same API leveraged for viewing files through Microsoft Teams may fail due to this issue. Scope of Impact: Some users attempting to view contents of the Files tab in newly created Microsoft Teams channels in the desktop client may be impacted. Root Cause: A language configuration issue introduced by a recent change on the service side is resulting in impact to an API leveraged for serving files through Microsoft Teams. Next Update By: Friday, May 16, 2025, at 7:00 AM UTC Update: 15-May-2025 21:21 Title: Users may be unable to view contents of the Files tab in newly created Microsoft Teams channels in the desktop client User Impact: Users may be unable to view contents of the Files tab in newly created Microsoft Teams channels in the desktop client. More Info: Impact may also occur within Microsoft Teams on the web, and any file viewing requests reliant on the API leveraged for viewing files through Microsoft Teams may fail. Current Status: We've investigated our reproduction logs and have developed an expedited fix aimed at addressing and preventing future impact from occurring. We're preparing this fix for deployment now, while in parallel, we're continuing to investigate the source of the impact and whether this is correlated with a recent change made to the affected service. Scope of Impact: Some users attempting to view contents of the Files tab in newly created Microsoft Teams channels in the desktop client may be impacted. Next Update By: Friday, May 16, 2025, at 4:30 AM UTC Update: 15-May-2025 18:04 Title: Users may be unable to view contents of the Files tab in newly created Microsoft Teams channels in the desktop client User Impact: Users may be unable to view contents of the Files tab in newly created Microsoft Teams channels in the desktop client. More Info: Impact may also occur within Microsoft Teams on the web, and any file viewing requests reliant on the API leveraged for viewing files through Microsoft Teams may fail. Current Status: We've successfully reproduced the impact and confirmed that the issue is only reproducible in the Microsoft Teams desktop client; the web client is unaffected. We're reviewing logs captured from our reproduction and identified that requests to gather information are being misrouted as the sites themselves are created in English, rather than in the language of their organization's locale as intended. This results in requests to retrieve the document library failing due to the mismatch in languages. We're continuing to investigate our reproduction logs to determine why this is occurring and formulate potential remediation actions. Scope of Impact: Some users attempting to view contents of the Files tab in newly created Microsoft Teams channels in the desktop client may be impacted. Next Update By: Friday, May 16, 2025, at 2:30 AM UTC Update: 15-May-2025 16:20 Title: Users may be unable to view contents of the Files tab in newly created Microsoft Teams channels in the desktop client User Impact: Users may be unable to view contents of the Files tab in newly created Microsoft Teams channels in the desktop client. Current Status: Our review of the provided HAR logs is ongoing. We suspect that a fix for a previous issue with similar impact didn't appropriately deploy to some components of infrastructure as expected, resulting in requests from the API to retrieve the Files tab content routing incorrectly. We're attempting to reproduce this impact in our internal testing environment to confirm precisely where the failure occurs and determine our next troubleshooting steps. Scope of Impact: Some users attempting to view contents of the Files tab in newly created Microsoft Teams channels in the desktop client may be impacted. Next Update By: Thursday, May 15, 2025, at 10:30 PM UTC Update: 15-May-2025 14:20 Title: Users may be unable to view contents of the Files tab in newly created Microsoft Teams channels in the desktop client User Impact: Users may be unable to view contents of the Files tab in newly created Microsoft Teams channels in the desktop client. Current Status: Our initial review of the errors in the ULS logs suggests the issue may be due to the API responsible for providing the Files contents returning an incorrect string, resulting in impact. We're investigating why this string is being returned, and we've reached out to a subset of affected users to request a reproduction of impact while capturing HTTP Archive format (HAR) logs to assist our investigation into the source of the issue. Scope of Impact: Some users attempting to view contents of the Files tab in newly created Microsoft Teams channels in the desktop client may be impacted. Next Update By: Thursday, May 15, 2025, at 8:30 PM UTC Update: 15-May-2025 12:14 Title: Users may be unable to view contents of the Files tab in newly created Microsoft Teams channels in the desktop client User Impact: Users may be unable to view contents of the Files tab in newly created Microsoft Teams channels in the desktop client. Current Status: We're reviewing Unified Logging Service (ULS) logs and are analyzing errors occurring during requests to retrieve contents from the Files tab to better understand how impact is manifesting and assist our investigation into the source of the issue. Scope of Impact: Some users attempting to view contents of the Files tab in newly created Microsoft Teams channels in the desktop client may be impacted. Next Update By: Thursday, May 15, 2025, at 6:30 PM UTC Update: 15-May-2025 10:19 Title: Users may be unable to view contents of the Files tab in newly created Microsoft Teams channels in the desktop client User Impact: Users may be unable to view contents of the Files tab in newly created Microsoft Teams channels in the desktop client. Current Status: We're reviewing details provided in the support case to determine the next steps needed to resolve this issue. Scope of Impact: Some users attempting to view contents of the Files tab in newly created Microsoft Teams channels in the desktop client may be impacted. Next Update By: Thursday, May 15, 2025, at 4:30 PM UTC