1 min lesson
Capture the network
Explain the practical point behind "A HAR capture or the Developer Tools Network tab shows failed and slow model requests, timeouts and payload sizes."
Step 1 of 3
Capture the networkthe AI-native part of the stack
Most of what makes Cursor Cursor happens over the wire. A HAR capture or the Developer Tools Network tab shows failed and slow model requests, timeouts and payload sizes. Map the status code to a cause fast.
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Advanced table
Reference table
- Signal
- 401 / 403
- Likely cause
- Auth or entitlement - token expired, plan or org policy
- Signal
- 407
- Likely cause
- Corporate proxy authentication required
- Signal
- 429
- Likely cause
- Rate limit - too many requests or quota hit
- Signal
- 5xx
- Likely cause
- Backend error or model-serving incident
- Signal
- Timeout / ECONNRESET
- Likely cause
- Blocked or dropped connection; firewall or transit
- Signal
- TLS / cert error
- Likely cause
- Inspecting proxy (MITM) or local clock skew
- Signal
- 200 but slow
- Likely cause
- Backend latency or a huge prompt payload
| Signal | Likely cause |
|---|---|
| 401 / 403 | Auth or entitlement - token expired, plan or org policy |
| 407 | Corporate proxy authentication required |
| 429 | Rate limit - too many requests or quota hit |
| 5xx | Backend error or model-serving incident |
| Timeout / ECONNRESET | Blocked or dropped connection; firewall or transit |
| TLS / cert error | Inspecting proxy (MITM) or local clock skew |
| 200 but slow | Backend latency or a huge prompt payload |
Status code first narrows client-vs-server before you read a single log line.
A frozen UI is rarely a UI bug. It's often a downstream effect of a stuck network call waiting on a timeout or an agent loop spinning on the same step. Correlate timestamps across the console, the network capture and any server trace you're given - the cause is usually the event just before the symptom, in a different layer.