"Internal Error: Sub-system: MLS, File: /quartus/synth/mls/mls_netlist.cpp" Error

Hello,

Whenever I try to compile a design that I am currently working on, I always receive this error message:

"Internal Error: Sub-system: MLS, File: /quartus/synth/mls/mls_netlist.cpp, Line: 2016

cloned_sgate != 0

Stack Trace:

0x8bd44: MLS_ROOT::delete_mls_netlist + 0xb3e4

0xafee0: MLS_ROOT::clone_mls_netlist + 0x23840

0xb062f: MLS_ROOT::clone_mls_netlist + 0x23f8f

0x553db: MLS_INTERFACE::MLS_INTERFACE + 0x1762b

0x3a1c2: MLS_INTERFACE::get_ready + 0x4472

0x336d5: MLS_INTERFACE::~MLS_INTERFACE + 0x17345

0x3519a: MLS_INTERFACE::call_named_function + 0x82a

0x34f38: MLS_INTERFACE::call_named_function + 0x5c8

0x3c659: MLS_ROOT::start_from_mls_netlist + 0x49

0x613ef: scl_start + 0x5ba8f

0x656c3: scl_start + 0x5fd63

0x2e374: scl_start + 0x28a14

0x2ef1d: scl_start + 0x295bd

0x2f47f: scl_start + 0x29b1f

0x5475: scl_run_parallel_mls_script + 0xfd5

0x128ed: qexe_get_command_line + 0x206d

0x1573e: qexe_process_cmdline_arguments + 0x59e

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

0x159bc: BaseThreadInitThunk + 0xc

0x2a2e0: RtlUserThreadStart + 0x20

End-trace

Quartus II 64-Bit Version 13.1.0 Build 162 10/23/2013 SJ Web Edition"

From the message above, I believe that this is a netlist error, however I am not sure what is specifically causing a netlist error.

Has anyone ever encountered this message? Thank you.