You may see this warning during timing analysis in the Quartus® Prime Standard edition software version 16.0 Update 2 and earlier. The warning occurs when compiling a MAX®10 design containing the altera_onchip_flash component.
Apply the following constraints to your Synopsys Design Constraint (.sdc) file manually to work around this problem.
create_generated_clock -name flash_se_neg_reg -divide_by 2 -source [get_pins -compatibility_mode { *altera_onchip_flash:*onchip_flash_0|altera_onchip_flash_avmm_data_controller:avmm_data_controller|flash_se_neg_reg|clk }] [get_pins -compatibility_mode { *altera_onchip_flash:*onchip_flash_0|altera_onchip_flash_avmm_data_controller:avmm_data_controller|flash_se_neg_reg|q } ]
This problem is scheduled to be fixed in a future release of the Quartus Prime Standard edition software.