This error occurs when a For Loop configured for parallel execution contains a Boolean control with latch mechanical action. The first loop instance to read the Boolean control with latch action resets the Boolean value to the default.
To correct this error, select a different mechanical action, remove the Boolean control, or disable parallelism on the For Loop. To disable parallelism on the For Loop, right-click the For Loop, select Configure Iteration Parallelism from the shortcut menu, and remove the checkmark from the Enable loop iteration parallelism checkbox in the For Loop Iteration Parallelism dialog box.