The RxErr status will be asserted after reseting the P-Tile Intel® FPGA IP for PCI Express with the pld_clrpcs_n[1:0] ports.
According to the PCI Express Base specification revision 4.0 version 1.0, sticky registers including RxErr status are not cleared after any type of conventional reset (cold, warm, or hot).
Clear the RxErr status in the PCI Express configuration space register before checking the RxErr status during data transaction.
This behaviour will not be changed in a future release of the Intel® Quartus® Prime Pro Edition Software.