ID:13101 Not allowed to move at least <number> registers due to user assignments

CAUSE: You attempted to optimize netlists by directing the Quartus Prime software to perform gate-level register retiming. However, the Quartus Prime software cannot move the specified number of registers because either you set the Netlist Optimizations logic option to Never allow or your set the Preserve Register logic option to on for these registers. The number of registers reported in this message may be lower than the actual number of registers with user assignments, because some registers may not be allowed to be moved for other reasons.

ACTION: If you want to allow the Quartus Prime software to move these registers, set the Netlist Optimizations logic option to Always Allow, or set the Preserve Register logic option to off. Otherwise, no action is required.