Internal Error: Sub-system: SUTIL, File: /quartus/synth/sutil/sutil_wiring_helper.cpp, Line: 242

Hi, while synthesising on Quartus Version 19.1.0 Build 240 03/26/2019 SJ Pro Edition for Arria 10 10AX115N2F45E1SG (Terasic de5a-net-ddr4 board) i get this internal error message which I don't understand, can someone help? Error occurring both on Linux Debian 10 and Windows 10.

Error message:

Internal Error: Sub-system: SUTIL, File: /quartus/synth/sutil/sutil_wiring_helper.cpp, Line: 242
cdb_is_connected (old_iterm)
Stack Trace:
0x5f44b: sutil_copy_fanin + 0x167 (SYNTH_SUTIL)
0x9888c: algs_ram_copy_fanin + 0x9c (SYNTH_ALGS)
0x9dd9e: ALGS_RAM_OPT_CONVERT_TDP_TO_SDP::copy_ram_input_ports_from_tdp_to_sdp + 0x3e (SYNTH_ALGS)
0x9d1fc: ALGS_RAM_OPT_CONVERT_TDP_TO_SDP::convert_tdp_with_unused_ports_to_sdp + 0x27c (SYNTH_ALGS)
0x9ce8b: ALGS_RAM_OPT_CONVERT_TDP_TO_SDP::optimize + 0xab (SYNTH_ALGS)
0x994a7: ALGS_RAM_OPTIMIZATION::optimize + 0xe7 (SYNTH_ALGS)
0x98f6c: ALGS_RAM_OPTIMIZATION::run + 0xbc (SYNTH_ALGS)
0x647cc: opt_pre_optimize_ram_nodes + 0x1dc (SYNTH_INFER)
0x5db3: OPT_RAM_INFERENCE::infer_ram_blocks + 0xb3 (SYNTH_INFER)
0x4cf9b: RTL_SCRIPT::call_ram_rom_fns + 0x42f (SYNTH_OPT)
0x49e66: RTL_SCRIPT::call_named_function + 0x8d6 (SYNTH_OPT)
0x48c56: RTL_SCRIPT::process_script + 0x5ba (SYNTH_OPT)
0x9c495: opt_run_pre_parallel_rtl + 0x23d (SYNTH_OPT)
0xbc91c: SYNTH::QIS::SYNTHESIS_FLOW::high_level_synthesis + 0x28c (synth_qis)
0xbf8d2: SYNTH::QIS::SYNTHESIS_FLOW::run_current_phase + 0x282 (synth_qis)
0xbfd3d: SYNTH::QIS::SYNTHESIS_FLOW::run_full_flow + 0x30d (synth_qis)
0x525a7: QIS_RTL_STAGE::IMPL::synthesize + 0x4b7 (synth_qis)
0x1b178: qis_synthesize + 0x1d8 (synth_qis)
0x16442: TclNRRunCallbacks + 0x62 (tcl86)
0x17c4d: TclEvalEx + 0x9ed (tcl86)
0xa6a8b: Tcl_FSEvalFileEx + 0x22b (tcl86)
0xa5136: Tcl_EvalFile + 0x36 (tcl86)
0x14ebc: qexe_evaluate_tcl_script + 0x3fc (comp_qexe)
0x13f72: qexe_do_tcl + 0x4b2 (comp_qexe)
0x1a34e: qexe_run_tcl_option + 0x5ee (comp_qexe)
0x18185: QCU::DETAIL::intialise_qhd_and_run_qexe + 0x95 (comp_qcu)
0x28f9c: qcu_run_tcl_option + 0x2ec (comp_qcu)
0x19c58: qexe_run + 0x438 (comp_qexe)
0x1ad8a: qexe_standard_main + 0x26a (comp_qexe)
0x34d9: qsyn2_main + 0x129 (quartus_syn)
0x149f8: msg_main_thread + 0x18 (CCL_MSG)
0x1609e: msg_thread_wrapper + 0x6e (CCL_MSG)
0x20fa0: mem_thread_wrapper + 0x70 (ccl_mem)
0x13f7d: msg_exe_main + 0x20d (CCL_MSG)
0x4dd4: __scrt_common_main_seh + 0x11c (quartus_syn)
0x17bd3: BaseThreadInitThunk + 0x13 (KERNEL32)
0x6ce50: RtlUserThreadStart + 0x20 (ntdll)

End-trace