---
title: "REST Service Error: 503 Service Unavailable (Tenant Under Maintenance)"
description: "REST Service Error: 503 Service Unavailable (Tenant Under Maintenance)"
keywords: "REST Service Error: 503 Service Unavailable (Tenant Under Maintenance)"
url: "https://myrapidi.com/wiki/rest_service_error_503_service_unavailable_tenant_under_maintenance"
locale: "en"
published: "2026-09-01T10:52:09Z"
modified: "2026-09-01T10:52:10Z"
---

**Description**

This error occurs when a REST API call to a service receives an HTTP status code outside the 20x (success) range, indicating the request was not processed successfully.

`The REST service returned a status code that is not 20x - i.e. not OK - Status code received: 503 Service Unavailable Response body: {"error": {"code": "Upgrade","message": "Tenant under maintenance. Maintenance type: Upgrade"}}`

**Error Details**

- **Status Code:** 503 Service Unavailable
- **Error Code:** `Upgrade`
- **Message:**"Tenant under maintenance. Maintenance type: Upgrade"

**Cause**

The target tenant (commonly a Business Central or Dynamics 365 environment) is temporarily unavailable because it is undergoing a scheduled or in-progress upgrade. During this maintenance window, the tenant's API endpoints reject incoming requests to prevent data inconsistency.

**Resolution**

- Wait for the maintenance/upgrade to complete before retrying the request.
- Implement retry logic with exponential backoff for integration jobs that may run during maintenance windows.
- Check the tenant's admin center or service status page for an estimated maintenance completion time.
- If the issue persists beyond the expected maintenance window, contact the tenant administrator or platform support.