Warning Codes: What Is Your Camera Screen Trying to Tell You?

The most frequent call to our repair workshop begins with an alarmed photographer saying: "Technician! I pressed the shutter button, heard a grinding noise inside, and now 'Err' (or 'F--') is flashing on the top LCD! The camera won't shoot. Is it completely dead?"

Let us break down how to decode Nikon's primary diagnostic messages.

1. Flashing `Err` Message (System Error) — Primary Alert Marker!

An `Err` message indicates that the main logic processor detected optocoupler desynchronization or a mechanical jam. Internal sensors failed to receive confirmation of a completed shutter stroke or mirror cycle.

• Cause 1: A torn or misaligned shutter curtain blade.
• Cause 2: Stripped gear teeth in the mirror drive box assembly.
• What to Do: Remove the main battery for 5 minutes. If `Err` continues flashing upon powering back on — do not attempt to cock or release the shutter by force! Bring the body to a service shop.

2. Flashing `F--` Message (Aperture / Lens Contact Error)

An `F--` code is NOT related to shutter failure! It indicates lost electronic contact with the lens processor or an unlocked aperture ring on older D-series lenses.

Nikon System Error Decoding Table

Display Error Code	Mechanical / Electronic Cause	Recommended Technician Action
Flashing `Err`	Mechanical shutter or mirror box gear jam	Shutter diagnostics at a service facility
Solid `F--`	Dirty bayonet contacts or unlocked D-lens ring	Clean lens contacts with alcohol / Lock aperture ring to f/22
Flashing `r12` / `r08`	Remaining burst buffer capacity (Not an error!)	Continue shooting normally