Stellar Data Recovery Knowledge Base (KB) Articles 800

SKB1102

Troubleshooting the ‘Mailbox does not exist’ Error

Problem Description You are unable to start migration jobs or perform actions that require connecting to your Microsoft 365 (Office 365) tenant using Stellar Migrator for Exchange. The software displays one of the following (or similar) error messages: Mailbox does not exist This error prevents successful authentication and migration operations. Root Cause The Microsoft 365 admin account ..

Date Published 19 Dec 2025

Total Views 301

SKB1103

How to resolve "Mailbox Database Temporarily Unavailable" Error

The mailbox database is temporarily unavailable., Cannot open mailbox…”with details like: .Server = SN6PR06MB4621.namprd06.prod.outlook.com .mdbGuid = ... .mailboxGuid = ... It means that Exchange Online temporarily locked or offloaded the mailbox database associated with that mailbox. This usually happens due to throttling, load balancing, or too many concurrent connections hitting the mail..

Date Published 19 Dec 2025

Total Views 289

SKB1090

How to Provide Impersonate Rights through EAC?

In Exchange environments—whether on-premises or hybrid—certain service accounts or applications (like email migration tools, backup software, or third-party services) may require impersonation rights to access user mailboxes programmatically. This is especially common during mailbox migrations, automated data processing, or account audits. Impersonation allows a designated account to act ..

Date Published 03 Jun 2025

Total Views 284

SKB1098

Error: The server cannot service the request — EWS throttling or temporary unavailability

When performing mailbox operations via Exchange Web Services (EWS), you may encounter the error: "The server cannot service the request". This typically occurs due to throttling or temporary unavailability of the Exchange service (Office 365 or on-premises). Cause EWS Throttling: Office 365 or Exchange on-premises limits the number of concurrent requests per user or application to maintain se..

Date Published 13 Aug 2025

Total Views 282

SKB1109

Why is my SD card not getting scanned or detected in Stellar Photo Recovery on Mac?

If your SD card is not getting detected or scanned in Stellar Photo Recovery on Mac, the issue could be related to either a physical lock on the SD card or macOS security settings blocking the device connection. To resolve the issue, follow the steps below: 1. Check the Physical Lock Switch on the SD Card Almost all SD cards have a small mechanical slider on the side for write protection. If the..

Date Published 13 Feb 2026

Total Views 278

SKB1106

Unable to Connect to the Remote Server Error During EWS Migration

Error Message You may encounter the following error during migration or connection attempts: The request failed. Unable to connect to the remote server. Problem Description This error is a network-level failure that occurs before Exchange Online or EWS processes the request. The connection to the remote Exchange service cannot be established at that moment. This is a temporary issue..

Date Published 19 Dec 2025

Total Views 270

SKB1105

Underlying Connection Was Closed Error During EWS Migration

Error Message During migration or mailbox processing, you may see the following error: The request failed. The underlying connection was closed: An unexpected error occurred on a send. Problem Description This error is a network-level failure that commonly occurs during EWS migrations, especially when migrating a large number of items or large mailbox data. The connection between the migratio..

Date Published 19 Dec 2025

Total Views 269

SKB1101

How to resolve the Error “Insufficient privileges to complete the operation”?

Issue When selecting Microsoft 365 (M365) as the source or target during migration, users may encounter the error message: “Insufficient privileges to complete the operation” Cause The error appears if the application required for authentication is not properly registered in Microsoft Entra ID (Azure AD) or missing necessary permissions. Resolution To resolve this issue, ensure that applicat..

Date Published 18 Sep 2025

Total Views 266

SKB1104

Error: 503 Server Unavailable During Exchange Online (EWS) Migration

A 503 – Server Unavailable error from Exchange Online is one of the most common failures during EWS migrations, and it always means: Exchange/Office 365 is temporarily refusing your connection because of throttling, overload, or mailbox database movement. This is NOT a permanent failure. It is a temporary block. Causes: 1. Throttling (Most Common) Microsoft heavily throttles EWS: • ..

Date Published 19 Dec 2025

Total Views 265

SKB1092

How to Fix “The SMTP Address Format Is Invalid” Error in Exchange?

If you’re seeing the error “The SMTP address format is invalid” in Exchange, it usually means you’ve entered an email address in the wrong format. This often happens when using a domain-style login instead of a proper email address. Why This Happens Exchange expects a valid SMTP (email) address. When you enter a username like domain\user, it doesn’t qualify as a routable email address..

Date Published 03 Jun 2025

Total Views 263