Can't find mono-2.0-bdwgc.pdb for 2018.2.3f1 on http://symbolserver.unity3d.com

I need mono-2.0-bdwgc.pdb to solve the infinte loop problem. I have tried VS to debug the crash problem. Setting the symbol path to http://symbolserver.unity3d.com. But its not working. The mono-2.0-bdwgc.pdb can't be loaded. And i tried in windbg, the problem still exists. I have set environment variable _NT_SYMBOL_PATH to "cache*C:\Users\SYF\AppData\Local\Temp\SymbolCache;srv*http://msdl.microsoft.com/download/.../symbols;srv*http://symbolserver.unity3d.com/". Still have a error: Symbol file could not be found. Did i miss something?

 

If i specific the Symbol downloaded in http://symbolserver.unity3d.com manually. The symbol file just can't be loaded. the symbol on symbolserver seems a different fomat? I see the symbol file is mono-2.0-bdwgc.pd_, if i rename to
mono-2.0-bdwgc.pdb. It can't be loaded in VS. I don't konw how to use the symbol files in symbolserver. Anybody can help? That's my vs config:

 

Same problem. Trying to forensically debug a hang from a dump created with ProcDump

No source found for 'c:\buildslave\mono\build\external\bdwgc\mark.c'

DBGHELP: mono_2_0_bdwgc - private symbols & lines