"ERR" message, no metering or shutter release

When I press the shutter release button, the mirror lifts and returns. The shutter does not open, though, and the camera will not meter or autofocus. This happes with alle the lenses I have tested on the camera, and these lenses work fine on other cameras. The aperture registration tab seems to work fine.

Does anyone have experience with this kind of error? I wonder if maybe the shutter assembly is broken and needs to be replaced…