From this question: Is it possible to download program database (PDB) files of Microsoft Windows binaries without installing any software?

and the answer from @chentiangemalc:

You can also look for structure starting with signature RSDS (0x53445352),   
is followed by a GUID (16 bytes), 
a counter (4 bytes) and then the PDB pathname.

This works for most cases.

Except for this one:

I have a dll System.Collections.dll and imported to dotpeek. The GUID is 016f38124dcc4f82a73b12c7baf82e3e which doesn't work.


enter image description here

The dotpeek loaded the pdb from blew url:

Downloader: http://msdl.microsoft.com/download/symbols/system.collections.pdb/552b6fdf67184d5ab8ee8c8887f505b2FFFFFFFF/system.collections.pdb -> ok, 41.9 KB

Not sure where 552b6fdf67184d5ab8ee8c8887f505b2FFFFFFFF comes from?

This is the result from dumpbin:

Debug Directories

    Time Type        Size      RVA  Pointer
-------- ------- -------- -------- --------
C8A1BD67 cv            66 00009F38     8138    Format: RSDS, {016F3812-4DCC-4F82-A73B-12C7BAF82E3E}, 1, /_/artifacts/obj/System.Collections/ref/net6.0-Release/System.Collections.pdb
00000000 pdbhash       27 00009F9E     819E    SHA256: 12 38 6F 01 CC 4D 82 5F 67 3B 12 C7 BA F8 2E 3E 67 BD A1 48 68 C7 9C 0F 1A 0E 5C 92 0D E7 E9 EC
00000000 repro          0 00000000        0
  • Have you considered searching via winbindex.m417z.com/?file=system.collections.dll ...? Also of relevance this and this and -- if you know Python -- this.
    – 0xC0000022L
    Sep 6, 2023 at 21:13
  • Also iirc ms introduced a portable pdb format mostly targeting c# .net bin with magic BJSB NOT sure if those pdbs follow the guid age format
    – blabb
    Sep 7, 2023 at 5:42
  • Aside from @blabb's remark, I also recall that thanks to /Brepro the timestamp values are now deterministic and so different binaries (different file hashes) may share the same code and the same symbols.
    – 0xC0000022L
    Sep 7, 2023 at 9:58
  • Thanks guys. The dll I posted is a reference assembly which doesn't have symbols uploaded. What we really need is the corresponding implementation assembly.
    – Min Huang
    Oct 18, 2023 at 9:00

1 Answer 1


though both portable pdb and /Brepro are recent developments post the GUID age compressed file format of pdb

for your specific case the pdb does not seem to exist in ms symbol servers.

:\>wget -c -U="Microsoft-Symbol-Server/" "http://msdl.microsoft.com/download/symbols/system.collections.pdb/016F38124DCC4F82A73B12C7BAF82E3E1/system.collections.pdb"

HTTP request sent, awaiting response... 404 Not Found <<<<<<<<<<<<<<<<<<<<<<-----------------
2023-09-07 21:32:02 ERROR 404: Not Found.

:\>wget -c -U="Microsoft-Symbol-Server/" "http://msdl.microsoft.com/download/symbols/system.collections.pdb/552B6FDF67184D5AB8EE8C8887F505B21/system.collections.pdb"

HTTP request sent, awaiting response... 200 OK
Length: 284160 (278K) [application/octet-stream]
Saving to: 'system.collections.pdb'

100%[==============================================================================>] 284,160      249KB/s   in 1.1s

2023-09-07 21:32:07 (249 KB/s) - 'system.collections.pdb' saved [284160/284160]

you can check this answer of mine for some more relevant details about fetching the pdb without dbghelp or symsrv by using utilities like wget,curl,httpget etc

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