Compare another user and safe mode

macOS gives you two built-in comparison environments, and each one removes a different set of variables.

A fresh local account removes the original user’s login items, preferences, and application state from the comparison. Create one in System Settings → Users & Groups; it costs nothing and you can delete it after the investigation.

Safe Mode changes startup behavior and performs limited checks. It loads only required system components, blocks login items and third-party startup software, and verifies the startup disk. On Apple silicon: shut down, hold the power button until “Loading startup options” appears, select the startup disk while holding Shift, and choose “Continue in Safe Mode”. On Intel Macs, hold Shift right after power-on.

Confirm you are really in Safe Mode before trusting the test:

system_profiler SPSoftwareDataType | grep "Boot Mode"
# Boot Mode: Safe

If that says Normal, the Shift key did not register and your comparison is worthless.

Run the identical reproduction

Run the same exact reproduction in the original account, a clean account, and Safe Mode where appropriate. “Same exact” is the whole method: same file, same steps, same network. Record what changes and what remains:

Original account:  crash on export, every time
Clean account:     no crash, same file, same steps
Safe Mode:         not tested (symptom already isolated to user scope)

Interpret without over-claiming

If a clean account works, investigate user-scoped state. The suspects are the original account’s preferences, containers, caches, and login items — which you already know how to trace by scope.

If Safe Mode works, inspect startup software and extensions. Something that loads at login or startup is interfering, and the next step is disabling those items one at a time in the normal boot.

Neither result names the cause by itself. These are scope-narrowing experiments, not verdicts. Safe Mode also clears some caches as a side effect, so “fixed after one Safe Mode boot” may just mean a cache was rebuilt — note it, reboot normally, and confirm the symptom is actually gone.