What an iPhone panic-full is and how to read its signatures
Every time an iPhone suffers a kernel panic — a collapse of the operating system core — iOS writes a complete forensic report of the incident: the panic-full file. For a repair technician, that file is the equivalent of an aircraft's black box: it records which component failed, when, and under what conditions. Knowing how to read it turns an hours-long diagnosis into a minutes-long one.
Why does the iPhone generate this file?
The iOS kernel constantly monitors the device's critical components: thermal sensors, coprocessors, data buses, memory. When it detects a condition it can't handle safely — a sensor that disappeared, a chip that won't respond, a missing thermal reading — it would rather stop the entire system than risk greater damage (for example, charging the battery without being able to read its temperature). That emergency halt is the kernel panic, and the panic-full is its record.
Where to find the panic-full
- On the iPhone: Settings → Privacy & Security → Analytics & Improvements → Analytics Data.
- Look for the files whose name starts with
panic-full-followed by the date and time. - Tap it and use the share icon to send it (AirDrop, email, etc.).
- Workshop alternative: pull it with 3uTools or iMazing from a computer — useful when the device restarts too fast to navigate the settings.
The anatomy of the log
The file looks intimidating — hundreds of thousands of characters — but the diagnostic information is concentrated in just a few fields:
"product"— the internal model identifier (e.g.iPhone11,6= iPhone XS Max). Careful: it does not match the commercial name."os_version"— the iOS version at the moment of the panic."panicString"— the golden line: it describes the exact cause of the collapse and names the signature of the component involved.- The rest (call stacks, task lists, register dumps) is context that rarely changes the diagnosis, but hides clues in tough cases.
The most common signatures and what they mean
| Signature in the log | What it means | Usual suspect |
|---|---|---|
Missing sensor: mic2 | The rear microphone stopped responding | Charging flex / power-button flex depending on model |
Missing sensor: prs0 | The barometer isn't showing on the bus | Charging flex (the sensor lives there) |
Missing sensor: tg0b | No reading from the battery thermistor | Battery, connector or battery I2C/SMBus lines |
AOP PANIC | The Always-On coprocessor failed managing sensors | Proximity/ambient-light sensors, top flex, audio |
SMC PANIC | The power controller detected an abnormal condition | Charging circuits, wireless charging, power |
watchdog timeout | A component didn't respond for 180 s | Coprocessors or main-bus peripherals |
PCIe / link failures | Communication with a high-speed chip was lost | NAND, baseband modem, Wi-Fi |
The same signature can point to different components depending on the model — the mic2 of an iPhone 11 doesn't live on the same flex as an XS Max's. That's why serious diagnosis always cross-references signature + exact model.
Got a panic-full in hand right now?
Upload it to iPanic Analyzer Pro: the CoreMatch™ engine extracts the signatures, cross-references them against verified real repairs of the same model, and hands you the suspect component with its repair procedure. The first analysis is free.
Analyze my panic-full freeCommon mistakes when interpreting a panic-full
- Confusing the internal identifier with the commercial model —
iPhone11,6is an XS Max, not an iPhone 11. Diagnosing on the wrong model leads to the wrong flex. - Stopping at the word "watchdog" — many AOP/SMC panics mention the watchdog in their internal trace, but the root cause is something else. The main signature is at the start of the
panicString. - Blaming software by default — if the panicString names sensors or buses, restoring iOS won't resolve it.