This error occurs when a For Loop configured for parallel execution contains a Feedback Node.

To correct this error, try using a shift register instead of a Feedback Node 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.