Why do I get "Fatal Error: Access Violation at" when running quartus_syn or quartus_fit?

Description

Due to a problem in the Quartus® Prime Pro Edition Software versions 26.1 and earlier, and Quartus Prime Standard Edition Software versions 25.1 and earlier, compilation may terminate with a "Fatal Error: Access Violation" message during synthesis or fitting. This failure can occur intermittently, and the reported memory address may change between compilation runs.

You may observe one or more of the following behaviors:

Quartus® compilation fails during synthesis or fitting
The failure may occur in either of the following modules:
- quartus_syn (during synthesis)
- quartus_fit (during fitting)
The error message is similar to:
- *** Fatal Error: Access Violation at <<ADDRESS>>
- The reported memory address may change between runs.

The fatal error is followed by a stack trace that includes one of the failure signatures listed below.

```
CDB_SGATE_OTERM::adopt_fanouts
```
```
HDB_ASGN_CONTAINER::remove_assignment
```
```
LUTIL_DEVICE::get_fragment_from_subloc
```
```
STA_NODE::reset_tag_heads
```

DESIGN_HDB_ASSIGNMENT_CONVERTER::cleanup_after_conversion

```
BSYN_RTM_FLOP::IsExpired
```

RTM_ATOM_MGR::rip_out_simple_ff_for_bypass

```
IRTM_FF_QUEUE::remove_ff
```

PTI_BCM_TIMING_GRAPH::push_back_carry_hipi_clock_iterm

```
FTM_TREE_NODE::num_sgates
```

Stack traces may differ, even when compiling the same design.

Specific Failure Signatures:

Synthesis failure (quartus_syn): The crash report includes the following function call:

RTL_ADDER::aggressive_adder_balancing

Fitter failure (quartus_fit): The error occurs very early after the fitter starts, and the crash report includes the following function call:

qhd_reread_global_assign_from_qsf

Error Log Examples

Stack Trace example for crashes in quartus_syn

*** Fatal Error: Access Violation at 00007FFB92E2C63E Module: quartus_syn.exe

Stack Trace:

Quartus   0xc63d: CDB_SGATE_OTERM::adopt_fanouts + 0x2d (db_cdb_sgate)
Quartus   0x117e7: RTL_ADDER::shrink_iports + 0x1f7 (SYNTH_OPT)
Quartus   0x14a75: RTL_ADDER::create_binary_adder + 0x49e9 (SYNTH_OPT)
Quartus   0x45910: RTL_ADDER::restrict_adder_network + 0x84a (SYNTH_OPT)
Quartus   0x4f5d6: RTL_ADDER::aggressive_adder_balancing + 0x9d (SYNTH_OPT)
Quartus   0x11533: RTL_SCRIPT::call_common_rtl_fns + 0x1043 (SYNTH_OPT)
Quartus   0x115b5: RTL_SCRIPT::call_named_function + 0x8a2 (SYNTH_OPT)
Quartus   0x3a87a: RTL_SCRIPT::process_script + 0x62c (SYNTH_OPT)
Quartus   0x3a8e4: run_parallel_rtl + 0x1db4 (SYNTH_OPT)
Quartus   0x8509d: SYNTH_QIS::SYNTHESIS_FLOW::run_parallel_rtl_in_helper_processes + 0x285 (synth_qis)
Quartus   0x850d5: SYNTH_QIS::SYNTHESIS_FLOW::high_level_synthesis + 0x47d (synth_qis)
Quartus   0x8546d: SYNTH_QIS::SYNTHESIS_FLOW::run_current_phase + 0x286 (synth_qis)
Quartus   0x854d4: SYNTH_QIS::SYNTHESIS_FLOW::run_full_flow + 0x30d (synth_qis)
Quartus   0x859b7: QIS_RTL_STAGE_IMPL::synthesize + 0x467 (synth_qis)
Quartus   0x15b55: qis_synthesize + 0x245 (synth_qis)
Quartus   0x16442: TclNRRunCallbacks + 0x62 (tcl86)
Quartus   0x16f4d: TclEvalEx + 0x9ed (tcl86)
Quartus   0xa6ab8: Tcl_FSEvalFileEx + 0x22b (tcl86)
Quartus   0xa5136: Tcl_EvalFile + 0x36 (tcl86)
Quartus   0x15246: qexe_evaluate_tcl_script + 0x4e6 (comp_qexe)
Quartus   0x1143b: qexe_do_tcl + 0x46b (comp_qexe)
Quartus   0x1a70e: qexe_run_tcl_option + 0x5ee (comp_qexe)
Quartus   0x16451: QCU::DETAIL::initialize_qhd_and_run_qexe + 0xa1 (comp_qcu)
Quartus   0x1f8e2: qcu_run_tcl_option + 0x2f2 (comp_qcu)
Quartus   0x1b1ba: qexe_standard main + 0x26a (comp_qexe)
Quartus   0x29eb: qexe_run + 0x3eb (comp_qexe)
Quartus   0x1192p: qsyn2_main + 0x1a9p (quartus_syn)
Quartus   0x1e808: msg_main_thread + 0x18 (CCL_MSG)
Quartus   0x17021: msg_thread_wrapper + 0x71 (CCL_MSG)
Quartus   0x1c89d: mem_thread_wrapper + 0x70 (CCL_MEM)
Quartus   0x1b49d: msg_exe_main + 0x20d (CCL_MSG)
Quartus   0x2b6c: __scrt_common_main_seh + 0x11c (quartus_syn)
Quartus   0x2e8d6: BaseThreadInitThunk + 0x16 (KERNEL32)
Quartus   0x5b3b: RtlUserThreadStart + 0x2b (ntdll)

End-trace

Stack Trace example for crashes in quartus_fit

*** Fatal Error: Access Violation at 00007FFB8F79CFF7
Module: quartus_fit.exe

Stack Trace:
Quartus 0x1cff6: HDB_ASGN_CONTAINER::remove_assignment + 0x52 (DB_HDB)
Quartus 0x1cf71: HDB_ASGN_CONTAINER::destroy_assignment + 0x31 (DB_HDB)
Quartus 0xca69c: anonymous namespace::delete_all_global_assignments + 0x25c (comp_qhd)
Quartus 0xcc344: qhd_reread_global_assign_from_qsf + 0x384 (comp_qhd)
Quartus 0x51679: QHD_DATABASE_UTILS::load_design + 0x449 (comp_qhd)
Quartus 0x1e1e0: FIT2_DATABASE_EXPERT_QDB::load + 0x5b0 (comp_fit2)
Quartus 0x3xee: fit2_create_fitter_netlist + 0x3xee (comp_fit2)
Quartus 0x16442: TclNRRunCallbacks + 0x62 (tcl86)
Quartus 0x16f4d: TclEvalEx + 0x9ed (tcl86)
Quartus 0xa6ab8: Tcl_FSEvalFileEx + 0x22b (tcl86)
Quartus 0xa5136: Tcl_EvalFile + 0x36 (tcl86)
Quartus 0x15246: qexe_evaluate_tcl_script + 0x4e6 (comp_qexe)
Quartus 0x1143b: qexe_do_tcl + 0x46b (comp_qexe)
Quartus 0x1a70e: qexe_run_tcl_option + 0x5ee (comp_qexe)
Quartus 0x16451: QCU::DETAIL::initialize_qhd_and_run_qexe + 0xa1 (comp_qcu)
Quartus 0x1f8e2: qcu_run_tcl_option + 0x2f2 (comp_qcu)
Quartus 0x29eb: qexe_run + 0x3eb (comp_qexe)
Quartus 0x16f2d: qfit2_main + 0x82d (quartus_fit)
Quartus 0x1e808: msg_main_thread + 0x18 (CCL_MSG)
Quartus 0x17021: msg_thread_wrapper + 0x71 (CCL_MSG)
Quartus 0x1c89d: mem_thread_wrapper + 0x70 (CCL_MEM)
Quartus 0x1b49d: msg_exe_main + 0x20d (CCL_MSG)
Quartus 0x2b6c: __scrt_common_main_seh + 0x11c (quartus_fit)
Quartus 0x2e8d6: BaseThreadInitThunk + 0x16 (KERNEL32)
Quartus 0x5b3b: RtlUserThreadStart + 0x2b (ntdll)

End-trace

Resolution

This problem is currently scheduled to be resolved in a future release of the Quartus Prime Pro Edition Software and the Quartus Prime Standard Edition Software.

If you are using Quartus Prime Pro Edition Software version 26.1, apply the attached patch for your operating system:

Download the Linux or Windows patch package for your platform.
On Linux, install the patch package from the console.
On Windows, run the patch executable file.
Confirm the installation by opening the Quartus Prime GUI and checking the About window, or by running:

quartus_sh -v

If applying the patch is not possible, or if you need assistance with other Quartus Prime software versions, contact your local Altera support representative.