HTTP 408 Request Timeout
The server didn't get a complete request in time. The client should retry.
What it means
408 means the server gave up waiting for the request to finish. Either the network was slow, the client didn't send the request body in a reasonable time, or a connection was idle and the server closed it. Different from 504 (timeout talking to an upstream): 408 is the server timing out the client.
In monitoring, 408 from your service is usually a sign of slow client connections — mobile, congested networks, or intentionally-slow attackers (Slowloris-style). Some load balancers also return 408 when they close idle keep-alive connections.
Common causes
- Client connection idled and the server closed it
- Slow-upload attack (Slowloris)
- Mobile / congested network on the client side
- Load balancer keep-alive timeout shorter than the upstream's
How to fix it
- 1Tune client and server timeouts to be in alignment
- 2Retry the request from the client
- 3Investigate slow-upload attacks if 408s spike suspiciously
How Uptimera reports 408
Uptimera flags 408 as down. Sustained 408s under normal load usually indicate timeout misconfigurations in your load balancer or web server.
Related codes
Gateway Timeout
A proxy in front of your app waited too long for an upstream response and gave up.
Service Unavailable
The server is temporarily unavailable — overloaded, in maintenance, or intentionally not accepting traffic.
Too Many Requests
Rate-limited. The client is sending too many requests too fast.
Catch 408s before your customers do
Uptimera monitors your URLs from multiple regions and alerts the moment a 408 starts firing. Free plan included.