Add note re: wrong error when logging in to read replica with bad creds

Author: zoran-rilak-msft

azure-sql/managed-instance/doc-changes-updates-known-issues.md

@@ -22,6 +22,7 @@ This article lists the currently known issues with [Azure SQL Managed Instance](
 
 | Issue | Date discovered | Status | Date resolved |
 | --- | --- | --- | --- |
+| [Misleading error message when connecting to a read replica using invalid credentials](#misleading-error-message-when-connecting-to-a-read-replica-using-invalid-credentials) | February 2026 | 
 | [Modifying backup retention period for the free offer](#modifying-backup-retention-period-for-the-free-offer) | June 2025 | Has workaround | |
 | [Login to read-secondary failed due to long wait on "HADR_DATABASE_WAIT_FOR_TRANSITION_TO_VERSIONING"](#login-to-read-secondary-failed-due-to-long-wait-on-hadr_database_wait_for_transition_to_versioning) | April 2025 | Has workaround | |
 | [Interim guidance on 2024 time zone updates for Paraguay](#interim-guidance-on-2024-time-zone-updates-for-paraguay) | March 2025 | Has workaround | |
@@ -225,6 +226,10 @@ CLR modules in SQL Managed Instance and linked servers or distributed queries th
 
 ## No resolution
 
+### Misleading error message when connecting to a read replica using invalid credentials
+
+When attempting to connect to a Business Critical tier instance's read-secondary replica via ApplicationIntent=ReadOnly using invalid credentials, the instance may report an error indicating that the master database is read-only instead of correctly reporting that the credentials are invalid.
+
 ### Differential backups aren't taken when an instance is linked to SQL Server
 
 When you configure a [link](managed-instance-link-feature-overview.md) between SQL Server and Azure SQL Managed Instance, automated full and transaction log backups are taken on the SQL managed instance, whether or not it's in the primary role. However, differential backups aren't currently taken, when can lead to longer than expected restore times.