HTTP 101 Switching Protocols vs 525 SSL Handshake Failed
HTTP 101 (Switching Protocols) is a 1xx Informational response, while 525 (SSL Handshake Failed) is a 5xx Server Error response. 101 indicates that the server understands the Upgrade header field request and indicates which protocol it is switching to. In contrast, 525 means that cloudflare-specific. SSL/TLS handshake with the origin server failed.
Description
The server understands the Upgrade header field request and indicates which protocol it is switching to.
When You See It
When upgrading from HTTP/1.1 to WebSocket, or to HTTP/2.
How to Fix
This is normal behavior during protocol upgrades. Ensure your client supports the target protocol.
Description
Cloudflare-specific. SSL/TLS handshake with the origin server failed.
When You See It
When origin SSL certificate is expired, misconfigured, or incompatible.
How to Fix
Check origin SSL certificate validity. Ensure TLS version compatibility. Renew expired certificates.
Key Differences
101 is a 1xx Informational response, while 525 is a 5xx Server Error response.
HTTP 101: The server understands the Upgrade header field request and indicates which protocol it is switching to.
HTTP 525: Cloudflare-specific. SSL/TLS handshake with the origin server failed.
You encounter 101 when when upgrading from HTTP/1.1 to WebSocket, or to HTTP/2.
You encounter 525 when when origin SSL certificate is expired, misconfigured, or incompatible.
When to Use Which
For 101 (Switching Protocols): This is normal behavior during protocol upgrades. Ensure your client supports the target protocol. For 525 (SSL Handshake Failed): Check origin SSL certificate validity. Ensure TLS version compatibility. Renew expired certificates.