How to Fix 406 Not Acceptable Error in cPanel
Posted about 3 months ago 3.8kWhat Causes 406 Error
Rare but frustrating: Server cannot respond with requested content characteristics.
Most Common Trigger
ModSecurity rule rejecting request due to unacceptable content in headers or body.
Check ModSecurity Hits
WHM → ModSecurity Tools → Hits List → Look for rule 406-related blocks.
Solutions
Disable Offending Rule
Find rule ID (often 958000 series) → Disable for domain or globally if safe.
Whitelist Headers
Add SecRuleEngine DetectionOnly or whitelist specific Accept headers.
Plugin or Theme Issue
Test by disabling security plugins or switching theme.
Common Scenarios Table
| Scenario | Cause | Fix |
|---|---|---|
| AJAX requests | ModSecurity | Disable rule 958000 |
| REST API calls | Header inspection | Whitelist Accept header |
| Form submission | Content-Type | Check encoding |