559 Connection Limit Stop

The HTTP 559 Connection Limit Stop status code is an unofficial server error specific to Akamai Enterprise Application Access (EAA). The platform returns this code when a user exceeds the service concurrent connection limit.

Table of Contents

Usage

Akamai EAA enforces connection limits to protect backend applications from resource exhaustion. The 559 error appears when an authenticated user establishes more than 50 WebSocket connections, or when a large volume of requests triggers rate limiting applied to the connecting IP address.

The default limit is 50 concurrent WebSocket connections per user. This cap prevents individual users from monopolizing connector resources and guards against connection-based attacks. Standard HTTP request-response cycles are less likely to trigger this limit because connections close after the response completes. Long-lived connections like WebSockets accumulate and reach the threshold faster.

The limit applies per connecting IP for authenticated users. Multiple users behind the same NAT gateway or corporate proxy share a single IP, making shared environments more susceptible to hitting the threshold.

Akamai's documentation gives 558 and 559 identical titles, descriptions, and solutions. The operational difference between the two codes is not documented by Akamai.

SEO impact

Search engines treat 559 responses as server errors. Persistent errors cause crawlers to reduce crawl frequency and eventually drop affected URLs from the index.

Example

A client sends requests through Akamai EAA. After exceeding the connection limit, the next request receives a 559.

Request

GET /api/inventory/check HTTP/1.1
Host: app.example.re
Accept: application/json

Response

HTTP/1.1 559 Connection Limit Stop
Date: Mon, 02 Mar 2026 14:40:00 GMT
Content-Type: text/html

<html>
<head><title>559 Error</title></head>
<body>
<h1>Connection Limit Stop</h1>
<p>Service concurrent connections exceeded</p>
</body>
</html>

How to fix

Reduce the number of simultaneous connections and the request rate from a single IP. Applications opening multiple WebSocket connections in parallel need connection pooling or multiplexing to stay within the 50-connection limit.

Close idle WebSocket connections. Applications opening connections without properly closing them accumulate stale connections against the limit. Implement heartbeat timeouts and close connections no longer sending or receiving data.

Review the application architecture. A single WebSocket connection carrying multiplexed messages replaces multiple individual connections. Protocols like Socket.IO and GraphQL subscriptions support multiplexing over a single transport connection.

For environments where multiple users share a single outbound IP (corporate NAT, VPN concentrator), the aggregate traffic from all users counts against the same IP threshold. Splitting traffic across multiple egress IPs or requesting a higher limit from Akamai support addresses this scenario.

Check for connection leaks in the client-side code. Browser developer tools and network monitors reveal open WebSocket connections the application failed to close during navigation or component teardown.

Takeaway

The 559 Connection Limit Stop status code is an Akamai EAA error triggered when an authenticated user exceeds the concurrent connection limit (default 50 WebSocket connections) or IP-based rate limit. Akamai documents 559 identically to 558.

See also

Last updated: March 12, 2026