In Quartus Prime Pro Edition software version 16.0, Import Design is not compatible with Project Clean - In Quartus Prime Pro Edition software version 16.0, Import Design is not compatible with Project Clean Description In Quartus Prime Pro Edition software version 16.0, Project > Clean Project is not compatible with Project > Import Design . If you run Import Design , the project will fail with Error(23035): Tcl error: ERROR: Cannot open project: aram . Resolution To workaround this issue: Do not use Project > Clean Project with Project > Import Design . Instead, use the Overwrite option from the Import Design menu or command line argument. If Clean Project was called, you can select Close project followed by Open project in the GUI before calling Import Design ; this fixes the invalid state. Custom Fields values: ['novalue'] Troubleshooting FB368505; True ['novalue'] ['FPGA Dev Tools Quartus® Prime Software Pro'] 16.1 16.0 ['Programmable Logic Devices'] ['novalue'] ['novalue'] ['novalue']