Last I heard...it was a public Saudi Arabian hanging.
The drop was too far for the weight of the man.
With hanging, there is a fairly slim margin of error.
Many heads have been popped off like this.
The hangman is looking for the "sweet spot" where the condemned drops just far enough to suffer a clean neck break.
Not enough of a drop and the condemned chokes to death slowly. Too much of a drop and his head pops off.
This has happened plenty in the US and Europe in the past.
Examples ??