Due to a problem in the Intel® Quartus® Prime Pro Edition Software versions 21.1 and later, you may see that nSTATUS generates a low pulse after nCONFIG and nSTATUS have gone high at the beginning of a reconfiguration operation that has interrupted a previous ongoing reconfiguration operation.
Figure 1 shows the unexpected low pulse generated by the nSTATUS signal.
If there was no ongoing reconfiguration operation previous to the unexpected low pulse in the nSTATUS signal, then it must be handled as a Recoverable Configuration Error as described in the Intel® Stratix® 10 Configuration User Guide or the Intel Agilex® Configuration User Guide.
To work around this problem, make your configuration controller ignore the unexpected low pulse on the nSTATUS signal and continue the reconfiguration process once nSTATUS has returned high. Ignoring the unexpected low pulse will allow your Intel® Stratix® 10 or Intel Agilex® 7 device to complete the reconfiguration process.
This problem is fixed starting with the Intel® Quartus® Prime Pro Edition Software version 21.3 for Intel Agilex® 7 devices and Intel® Quartus® Prime Pro Edition Software version 21.4 for Intel® Stratix® 10 devices.