Internal Error: Sub-system: PDP, File: /quartus/periph/pdp/pdp_placement_cache.cpp, Line: 890 Entry not found - Internal Error: Sub-system: PDP, File: /quartus/periph/pdp/pdp_placement_cache.cpp, Line: 890 Entry not found Resolution There is no workaround. This issue will be fixed in a future software release. Related Articles The BluePrint Platform Designer in the Quartus ® Prime Pro Edition software encounters an internal error when you interactively place mergeable cells such as phase-locked loops (PLLs) and CLKBUFs. Consider an example where you have two CLKBUFS that are merged. If you place the first CLKBUF and then interactively place the second CLKBUF in the same location as the first CLKBUF, the BluePrint GUI incorrectly unplaces the original cell before placing the second CLKBUF. Custom Fields values: ['novalue'] Troubleshooting FB323290; False ['novalue'] ['FPGA Dev Tools Quartus® Prime Software Pro'] novalue 15.1 ['Programmable Logic Devices'] ['novalue'] ['novalue'] ['novalue']