Admins experience intermittent failures adding, modifying or removing members from Exchange Online distribution groups

Title: Admins experience intermittent failures adding, modifying or removing members from Exchange Online distribution groups User impact: Admins experience intermittent failures adding, modifying or removing members from Exchange Online distribution groups. More info: Admins may intermittently receive an error stating, "Failed to update Members - Response Content is Null" when managing distribution group membership in the Microsoft 365 Admin Portal or Exchange Admin Center. As a workaround, admins can use Exchange Online PowerShell to add or remove members from affected distribution groups. Impact is specific to admins utilizing on-premises Exchange who are attempting to add or remove members from Exchange Online distribution groups. Current status: We've initiated the deployment of our fix, which is ongoing and has saturated through over 50 percent of the affected environment. We're continuing to monitor its progress as it continues and anticipate it will complete, remediating impact for all users, by our next scheduled communication update. Scope of impact: This issue impacts some on-premises Exchange admins attempting to add or remove members from Exchange Online distribution groups. This section may be updated as the investigation progresses. Start time: Tuesday, June 9, 2026, at 9:43 PM UTC Root cause: A conflict between a configuration and a recent update is preventing admins from adding or removing users from distribution groups for on-premises configurations. Next update by: Thursday, October 22, 2026, at 5:30 PM UTC

Title: Admins experience intermittent failures adding, modifying or removing members from Exchange Online distribution groups User impact: Admins experience intermittent failures adding, modifying or removing members from Exchange Online distribution groups. More info: Admins may intermittently receive an error stating, "Failed to update Members - Response Content is Null" when managing distribution group membership in the Microsoft 365 Admin Portal or Exchange Admin Center. As a workaround, admins can use Exchange Online PowerShell to add or remove members from affected distribution groups. Impact is specific to admins utilizing on-premises Exchange who are attempting to add or remove members from Exchange Online distribution groups. Current status: We've completed the validations for our fix, which we're preparing to deploy to the affected environment. We still anticipate deployment will begin by Thursday, October 15, 2026. Scope of impact: This issue impacts some on-premises Exchange admins attempting to add or remove members from Exchange Online distribution groups. This section may be updated as the investigation progresses. Start time: Tuesday, June 9, 2026, at 9:43 PM UTC Root cause: A conflict between a configuration and a recent update is preventing admins from adding or removing users from distribution groups for on-premises configurations. Next update by: Thursday, October 15, 2026, at 5:30 PM UTC

Title: Admins experience intermittent failures adding, modifying or removing members from Exchange Online distribution groups User impact: Admins experience intermittent failures adding, modifying or removing members from Exchange Online distribution groups. More info: Admins may intermittently receive an error stating, "Failed to update Members - Response Content is Null" when managing distribution group membership in the Microsoft 365 Admin Portal or Exchange Admin Center. As a workaround, admins can use Exchange Online PowerShell to add or remove members from affected distribution groups. Impact is specific to admins utilizing on-premises Exchange who are attempting to add or remove members from Exchange Online distribution groups. Current status: Our validations are taking longer than initially anticipated as we test the effectiveness of our code fix to ensure it fully remediates impact once deployed. We anticipate beginning deployment by Friday, October 15, 2026, and we aim to provide updates on our timeline to release as we complete our validation process. Scope of impact: This issue impacts some on-premises Exchange admins attempting to add or remove members from Exchange Online distribution groups. This section may be updated as the investigation progresses. Start time: Tuesday, June 9, 2026, at 9:43 PM UTC Root cause: A conflict between a configuration and a recent update is preventing admins from adding or removing users from distribution groups for on-premises configurations. Next update by: Thursday, October 8, 2026, at 5:30 PM UTC

Title: Admins experience intermittent failures adding, modifying or removing members from Exchange Online distribution groups User impact: Admins experience intermittent failures adding, modifying or removing members from Exchange Online distribution groups. More info: Admins may intermittently receive an error stating, "Failed to update Members - Response Content is Null" when managing distribution group membership in the Microsoft 365 Admin Portal or Exchange Admin Center. As a workaround, admins can use Exchange Online PowerShell to add or remove members from affected distribution groups. Impact is specific to admins utilizing on-premises Exchange who are attempting to add or remove members from Exchange Online distribution groups. Current status: We're deploying a code fix to our internal test environment to validate its efficacy in remediating the impact. We anticipate our validations will be completed by our next scheduled communications update, at which time we'll aim to provide a timeline for the broad deployment. Scope of impact: This issue impacts some on-premises Exchange admins attempting to add or remove members from Exchange Online distribution groups. This section may be updated as the investigation progresses. Start time: Tuesday, June 9, 2026, at 9:43 PM UTC Root cause: A conflict between a configuration and a recent update is preventing admins from adding or removing users from distribution groups for on-premises configurations. Next update by: Thursday, October 1, 2026, at 5:30 PM UTC

Title: Some admins may experience intermittent failures adding or removing members from Exchange Online distribution groups User impact: Admins may experience intermittent failures adding or removing members from Exchange Online distribution groups. More info: Admins may intermittently receive an error stating, "Failed to update Members - Response Content is Null" when managing distribution group membership in the Microsoft 365 Admin Portal or Exchange Admin Center. As a workaround, admins can use Exchange Online PowerShell to add or remove members from affected distribution groups. Impact is specific to admins utilizing on-premises Exchange who are attempting to add or remove members from Exchange Online distribution groups. Current status: After reviewing reports of impact and provided diagnostic data, we've isolated that when admins are attempting to add or remove members from Exchange Online distribution groups, there's a conflict between a configuration and a recent update which is preventing admins from being able to add or remove users from distribution groups for on-premises configurations. We’re removing the problematic behavior from our code flow with a new code fix. We aim to provide a timeline for code fix deployment to be initiated by our next scheduled update. Scope of impact: This issue impacts some on-premises Exchange admins attempting to add or remove members from Exchange Online distribution groups. This section may be updated as the investigation progresses. Start time: Tuesday, June 9, 2026, at 9:43 PM UTC Root cause: A conflict between a configuration and a recent update is preventing admins from adding or removing users from distribution groups for on-premises configurations. Next update by: Thursday, September 24, 2026, at 5:30 PM UTC

Title: Some admins may experience intermittent failures adding or removing members from Exchange Online distribution groups User impact: Admins may experience intermittent failures adding or removing members from Exchange Online distribution groups. More info: Admins may intermittently receive an error stating, "Failed to update Members - Response Content is Null" when managing distribution group membership in the Microsoft 365 Admin Portal or Exchange Admin Center. As a workaround, admins can use Exchange Online PowerShell to add or remove members from affected distribution groups. Current status: We've received reports from a subset of affected admins that the impact scenario documented in EX1466035 is still ongoing and additional analysis is required. We're reviewing the latest reports of impact to further our understanding and to determine our next troubleshooting steps. Scope of impact: This issue impacts some admins attempting to add or remove members from Exchange Online distribution groups. This section may be updated as the investigation progresses. Next update by: Wednesday, September 23, 2026, at 6:00 PM UTC