508 - Loop Detected
HTTP 508 Loop Detected means the server found an infinite loop while processing recursive or depth-based operations.
Last reviewed: March 13, 2026|Editorial standard: source-backed technical guidance
What Does Loop Detected Mean?
Recursive processing entered a cycle, so the server aborted evaluation to avoid unbounded loop execution.
Common Causes
- -WebDAV depth-infinity traversal hits cyclic bind graph and loop detector aborts recursive enumeration.
- -File synchronization walker follows symbolic link cycle and recursion guard triggers loop detected response.
- -CMS content reference graph contains parent-child cycle, causing repeated expansion of identical nodes.
How to Fix Loop Detected
- 1Identify recursion or graph traversal path that re-enters previously visited nodes.
- 2Add cycle detection and maximum-depth guards in traversal logic.
- 3Fix resource graph/model references that create unintended cyclic dependencies.
Step-by-Step Diagnosis for Loop Detected
- 1Capture traversal trace and identify first repeated node/path that triggers loop detection.
- 2Inspect resource graph relations and bindings for cycles or self-references.
- 3Review recursion guards, visited-node tracking, and depth limit settings.
- 4Retest with corrected graph and traversal guards under representative depth scenarios.
Traversal Path and Cycle Detection Audit
- -Trace recursive call graph with node IDs (example: parent references child that references same parent through alias).
- -Verify visited-node set logic (example: hash key excludes namespace, so cycles are not recognized until deep recursion).
Data Model and Dependency Graph Remediation
- -Inspect persisted relationship graph for cyclic bindings (example: folder bind operation creates cycle in WebDAV collection tree).
- -Audit workflow expansion logic (example: dependency resolver repeatedly re-queues already expanded task chain).
Implementation Examples
curl -i -X GET https://api.example.com/v1/resource
# Response:
# HTTP/1.1 508 Loop Detected
# {"error":"Loop Detected","code":"508"}const response = await fetch('https://api.example.com/v1/resource', {
method: 'GET',
headers: { 'Accept': 'application/json' }
});
if (response.status === 508) {
console.error('Handle 508 Loop Detected');
}import requests
response = requests.get(
'https://api.example.com/v1/resource',
headers={'Accept': 'application/json'}
)
if response.status_code == 508:
print('Handle 508 Loop Detected')How to Verify the Fix
- -Repeat recursive/depth-based operations and confirm 508 no longer appears.
- -Validate traversal completes within defined depth and performance bounds.
- -Monitor loop-detection and recursion-depth metrics for sustained stability.
How to Prevent Recurrence
- -Enforce cycle detection and max-depth checks in all recursive handlers.
- -Validate resource graph integrity with periodic cycle scans.
- -Add regression suites for known cyclic topology edge cases.
Pro Tip
- -trace canonical traversal fingerprints so repeated loop patterns can be auto-clustered and fixed at the model layer.
Decision Support
Compare Guide
429 Too Many Requests vs 503 Service Unavailable
Use 429 for caller-specific throttling and 503 for service-wide outages, so retry behavior, escalation paths, and incident ownership stay correct.
Compare Guide
500 Internal Server Error vs 502 Bad Gateway: Root Cause
Debug 500 vs 502 faster: use 500 for origin failures and 502 for invalid upstream responses at gateways, then route incidents to the right team.
Playbook
API Timeout Playbook (502 / 504 / DEADLINE_EXCEEDED)
Use this playbook to separate invalid upstream responses from upstream wait expiration and deadline exhaustion, and apply timeout budgets, safe retries, and circuit-breaker controls safely.
Playbook
Availability and Dependency Playbook (500 / 503 / ServiceUnavailable)
Use this playbook to separate origin-side 500 failures from temporary 503 dependency or capacity outages, then apply safe retry and escalation paths.
Official References
Provider Context
This guidance is specific to HTTP services. Always validate implementation details against official provider documentation before deploying to production.