Quartus II Internal Error on finishing fitting

[Altera_Forum]

Hi All, 

 I've posted about internal errors before, but now I am getting a different one. The code was compiling without issue until I changed an "if" condition to use a different register within the module, and now the code won't compile and generates the following error at 92% of the way through fitting. If anyone has any knowledge as to why this might be please let me know. Is re-installing the Quartus II software my only option, or is there something specific my code may be doing that could cause this? (Code snippet is also below)   Thanks for any help!  Variable definition (the first in input from a different module, the second is an output from a FIFO constructed within the module);  input FIFO_Read_Rq; . . . wire FIRFIFO_Rd_Empty;   Culpable IF statement (the first condition compiles fine, the second - shown here active, does not compile at all;    if(/*FIFO_Read_Rq == 1'b1 && */FIRFIFO_Rd_Empty == 1'b0)  begin   Out_Data[15:0] = PD_Data[15:0];   end  Internal Error Message;  Internal Error: Sub-system: HDB, File: /quartus/h/qtl_object_cache_sys.h, Line: 711 slice->m_locks == 0 Stack Trace:  0x959a0: HDB_ENUM_OPTION::get_value + 0x282a0   0x47e96: HDB_ACTION_PT_INSTANCE::find_design_unit + 0x4f6   0x2117: HDB_FILE_DEPENDENCIES::~HDB_FILE_DEPENDENCIES + 0x1d7   0x1fa3: HDB_FILE_DEPENDENCIES::~HDB_FILE_DEPENDENCIES + 0x63   0x40bb0: HDB_ACTION_PT_INSTANCE::~HDB_ACTION_PT_INSTANCE + 0x250   0x57a5c: HDB_CHIP::reset_visited_flag + 0x33c   0x5db48: HDB_CMP_ACTION_PT_INSTANCE::sweep_timegroups + 0xe8   0x5db6d: HDB_CMP_ACTION_PT_INSTANCE::sweep_timegroups + 0x10d   0x54a87: HDB_CMP_ACTION_PT_INSTANCE::close_pdb_and_clear_cache + 0x127   0x2cbb: HUT_UTIL::restore_cap_inst_from_pdb + 0xfb   0xa736: CSYN_EXPERT:: operator= + 0x89a6   0x45fe4: CSYN_ENV::restore_state + 0x104   0x2751: FSYN_ENV::restore_state + 0x31   0x11acb: CSYN_EXPERT:: operator= + 0xfd3b   0x6a1f: CSYN_EXPERT:: operator= + 0x4c8f   0x4d4b6: CSYN_EXPERT::run_single_algorithm + 0x296   0x4c340: CSYN_EXPERT::run_flow + 0xd0   0x4b891: CSYN_EXPERT::late_fsyn_flow + 0x291   0x48e5a: CSYN_EXPERT::do_physical_synthesis + 0x68a   0x5b888e: VPR_QI_FACADE::vpr_qi_fsyn_fus_init_chle_lib_api + 0xfd41e   0x2c9ad9: VPR_QI_FACADE::~VPR_QI_FACADE + 0xdad19   0x1c5cf9: VPR_QI_FACADE::vpr_qi_get_start_and_end_progress_bar_perc_for_fsyn + 0x1b05a9   0x1b80fd: VPR_QI_FACADE::vpr_qi_get_start_and_end_progress_bar_perc_for_fsyn + 0x1a29ad   0x19b275: VPR_QI_FACADE::vpr_qi_get_start_and_end_progress_bar_perc_for_fsyn + 0x185b25   0x1a2b8d: VPR_QI_FACADE::vpr_qi_get_start_and_end_progress_bar_perc_for_fsyn + 0x18d43d   0x1c5d5b: VPR_QI_FACADE::vpr_qi_get_start_and_end_progress_bar_perc_for_fsyn + 0x1b060b   0x1db717: VPR_QI_FACADE::vpr_qi_main + 0x27   0x2de91: fitapi_run_vpr + 0x71   0x46e18: FITCC_EXPERT::run_vpr + 0x138   0x48c0f: FITCC_EXPERT:: place_and_route + 0x14f   0x4aff1: FITCC_EXPERT::invoke_fitter + 0x711   0x4798: fcuda_execute + 0x1f8   0xbab9: fmain_start + 0x7f9   0x1525: Legacy_fitter_Init + 0x4b5   0x2618: Legacy_fitter_Init + 0x15a8   0x2168: Legacy_fitter_Init + 0x10f8   0xf8a6: TclInvokeStringCommand + 0xc6   0x112a8: TclEvalObjvInternal + 0x328   0x121b5: TclEvalEx + 0x8d5   0x12d48: TclEvalObjEx + 0x2d8   0x1abbd: Tcl_EvalObjCmd + 0xfd   0x112a8: TclEvalObjvInternal + 0x328   0x56917: TclExecuteByteCode + 0xe47   0xa2376: TclObjInterpProcCore + 0x76   0x112a8: TclEvalObjvInternal + 0x328   0x56917: TclExecuteByteCode + 0xe47   0xa2376: TclObjInterpProcCore + 0x76   0x112a8: TclEvalObjvInternal + 0x328   0x121b5: TclEvalEx + 0x8d5   0x7c117: Tcl_FSEvalFileEx + 0x1d7   0x7a626: Tcl_EvalFile + 0x36   0xc1ff: qexe_ipc_progress_bar_name + 0x12bf   0x11dd6: qexe_get_command_line + 0x1556   0x150d5: qexe_run_tcl_option + 0x585   0x1e03d: qcu_run_tcl_option + 0xb8d   0x156ed: qexe_process_cmdline_arguments + 0x54d   0x15851: qexe_standard_main + 0xa1     0xa7f8: msg_exe_fini + 0x58   0xaf3c: msg_exe_fini + 0x79c   0x1f14: MEM_SEGMENT_INTERNAL::~MEM_SEGMENT_INTERNAL + 0x194   0xb8bf: msg_exe_main + 0x8f     0x1841: BaseThreadInitThunk + 0x19   0x57508: RtlUserThreadStart + 0x20    End-trace   Quartus II 64-Bit Version 13.1.0 Build 162 10/23/2013 SJ Full Version

[Altera_Forum]

Internal errors are usually deterministic and re-installing Quartus won't help. The fact that it occurs in the fitter doesn't help, because your code makes it through synthesis and generates something that is passed to the fitter, so there is nothing "wrong" with your HDL. What are the fitter messages around it? Maybe you can see what's occurring and maybe there's a way to get around it. For example, if Physical Synthesis is occurring, maybe you could turn it off. What happens if you try a different seed?