Trigger a sysdiagnose by simultaneously pressing and releasing both volume buttons + sleep/wake (power) button.
Note: The sysdiagnose is triggered upon button release .
On an iPhone you will feel a short vibration when a sysdiagnose is successfully triggered .
Wait 3 minutes for the diagnostic gathering to complete .
iOS 11, if you own a Mac:
1. Go to Settings -> Privacy -> Analytics -> Analytics Data
2. Find "sysdiagnose-...." file .
3. Tap AirDrop it to your Mac to view.
iOS 10, 9 or if you own Windows
1. Sync device with iTunes on your host computer .
2. Find the file listed at the paths below under Log Locations, based on which platform and version you’re using .
Note: “~/Library/…” actually translates to: /Users/[Your User Name]/Library/…
The “/Users/[Your User Name]/Library/…” folder is hidden by default in macOS.
To expose the folder, hold the option key while clicking the Finder’s "Go" menu and the Library folder will appear in the menu.
Any time you see a placeholder like “[Your Device Name]” or, “[Your User Name]” you should replace that part of the path with your actual device’s name, or your computer user name.
C:\Users[YourUserName]\AppData\Roaming\Apple Computer\Logs\CrashReporter\MobileDevice\ [YourDeviceName]\DiagnosticLogs\sysdiagnose
Note: The AppData folder in Windows 8 is hidden by default. Click on the View menu item in a Windows navigation window and check the "Hidden
items" checkbox and the AppData folder will appear in the list of folders under C:\Users[DeviceName].
Important: Replace "[YourDeviceName]" or "[YourUserName]" in the file paths above with the actual device name for the iOS device, or the actual user name you use on your computer.
Source: Apple <a href="https://download.developer.apple.com/iOS/iOSLogs/sysdiagnoseLoggingInstructions.pdf" target="blank">sysdiagnoseLogging_Instructions.pdf (login required)