How to download a sqlservr.pdb symbol file

I just had to figure out how to do this so I figured a quick blog post is in order to save other people time in future.

If you ever need to use windbg to debug a SQL Server crash dump, or you want to capture call stacks using extended events (e.g. when debugging excessive spinlock contention), you’ll need the correct symbol file (sqlservr.pdb) to go with sqlservr.exe of the instance you’re interested in.

[Edit: May 2016] Download and install the Windows debugging tools from the Windows SDK here. This works on Windows Vista through 10 and Windows Server through 2016.

Now you’ll have a tool called symchk in the folder where windbg resides (for my laptop, “C:\Program Files (x86)\Windows Kits\10\Debuggers\x64”) – this is what will pull down sqlservr.pdb.

You need to point symchk at the executable you’re interested in, tell it where to put the sqlservr.pdb, and tell it the location of the Microsoft symbol server.

For me, the following worked:

C:\Users\Paul>cd C:\Program Files\Microsoft SQL Server\MSSQL12.SQL2014\MSSQL\Binn

C:\Program Files\Microsoft SQL Server\MSSQL12.SQL2014\MSSQL\Binn>“C:\Program Files (x86)\Windows Kits\10\Debuggers\x64\symchk” sqlservr.exe /s SRV*c:\symbols*http://msdl.microsoft.com/download/symbols

Then go to the c:\symbols directory, and find the directory called sqlservr.pdb. It will have one or more sub-directories with GUID names, so pick the one with today’s date and then copy the sqlservr.pdb from that directory into the \Binn directory.

Again, the command string to use once you’re in the SQL Server Binn directory is:

“C:\Program Files (x86)\Windows Kits\10\Debuggers\x64\symchk sqlservr.exe /s SRV*c:\symbols*http://msdl.microsoft.com/download/symbols

If you get an error “The filename, directory name, or volume label syntax is incorrect.”, the copy-paste inserted weird characters for the double-quotes so delete and reinsert them. Also make sure there’s a space between /s and SRV.

You’ll also need to do this for sqlos.dll, plus on  SQL Server 2012+ you’ll need to do it for sqlmin.dllsqldk.dll, sqllang.dll, sqlboot.dll, and on SQL Server 2014+ you’ll need to do qds.dll and sqltses.dll too otherwise call stacks won’t resolve properly. I usually just replace sqlservr.exe in the command above with *.dll and then I’ve got all the symbol files possible, but you can save time by only doing it for the strictly necessary files.

When you get to the analysis phase, if you don’t have all the correct symbols, your call stack will look something like this (an example where sqlmin.pdb and sqllang.pdb are missing:

XeSosPkg::wait_info::Publish+138 [ @ 0+0x0
SOS_Task::PreWait+176 [ @ 0+0x0
Ordinal1132+9ab [ @ 0+0x0
Ordinal1391+b8e [ @ 0+0x0
Ordinal429+c4e [ @ 0+0x0
Ordinal319+966 [ @ 0+0x0
0x000007FEF20B04E2
0x000007FEF20B0D27
0x000007FEF20B1ACC
0x000007FEF12204C1
0x000007FEF123A54B
0x000007FEF1239C84
0x000007FEF125DC2F
0x000007FEF1254EC7
SOS_Task::Param::Execute+21e [ @ 0+0x0
SOS_Scheduler::RunTask+a8 [ @ 0+0x0
SOS_Scheduler::ProcessTasks+29a [ @ 0+0x0
SchedulerManager::WorkerEntryPoint+261 [ @ 0+0x0
SystemThread::RunWorker+8f [ @ 0+0x0
SystemThreadDispatcher::ProcessWorker+3c8 [ @ 0+0x0
SchedulerManager::ThreadEntryPoint+236 [ @ 0+0x0
BaseThreadInitThunk+d [ @ 0+0x0
RtlUserThreadStart+21 [ @ 0+0x0

Where it should resolve every frame in the call stack and look something like this (the same example with all pdbs in place):

XeSosPkg::wait_info::Publish+138 [ @ 0+0x0
SOS_Task::PreWait+176 [ @ 0+0x0
EventInternal::Wait+1e3 [ @ 0+0x0
FCB::SyncWrite+104 [ @ 0+0x0
DBMgr::CopyModel+fe [ @ 0+0x0
DBMgr::CreateAndFormatFiles+966 [ @ 0+0x0
CStmtCreateDB::CreateLocalDatabaseFragment+682 [ @ 0+0x0
DBDDLAgent::CreateDatabase+f7 [ @ 0+0x0
CStmtCreateDB::XretExecute+8fc [ @ 0+0x0
CMsqlExecContext::ExecuteStmts<1,1>+400 [ @ 0+0x0
CMsqlExecContext::FExecute+a33 [ @ 0+0x0
CSQLSource::Execute+866 [ @ 0+0x0
process_request+73c [ @ 0+0x0
process_commands+51c [ @ 0+0x0
SOS_Task::Param::Execute+21e [ @ 0+0x0
SOS_Scheduler::RunTask+a8 [ @ 0+0x0
SOS_Scheduler::ProcessTasks+29a [ @ 0+0x0
SchedulerManager::WorkerEntryPoint+261 [ @ 0+0x0
SystemThread::RunWorker+8f [ @ 0+0x0
SystemThreadDispatcher::ProcessWorker+3c8 [ @ 0+0x0
SchedulerManager::ThreadEntryPoint+236 [ @ 0+0x0
BaseThreadInitThunk+d [ @ 0+0x0
RtlUserThreadStart+21 [ @ 0+0x0

There’s also a video by Erin that shows the process to go through – see here.

Enjoy!

18 thoughts on “How to download a sqlservr.pdb symbol file

  1. I started using WinDbg for the first time ever this week and I stumbled upon this blog post.

    I’m having trouble hammering my system to create a spinlock so that I get an extended event, so I can’t prove this myself, but if you were to set _NT_SYMBOL_PATH to symsrv*symsrv.dll*c:symbols2*http://msdl.microsoft.com/download/symbols for the sql server process, would sql server be able to use the pdb files in the symbol server cache as opposed to the directory itself to resolve the stack trace for extended events?

    I’ve recently discovered that _NT_SYMBOL_PATH is respected by tools in the microsoft compiler toolchain like link.exe, lib.exe, editbin.exe and dumpbin.exe, so I would suspect sqlservr.exe might behave the same way. If it didn’t behave the same way, I’d certainly file a connect bug suggesting it did.

    1. I don’t know Justin – ask Jonathan.

      Even just having SQL Server sitting doing nothing, it’s taking spinlocks in the background. What event are you trying to hit? Check out my spinlocks category where I show how to catch SOS_SCHEDULER_YIELD in XEvents.

  2. I have worked though a dozen or so posts relating to sqlservr.pdb availability for SQL 2008 R2 SP2 and SP3. I have been unable to download the sysmbolf files for for SQL 2008 R2 SP1. Can you provide any guidance? I always get the message

    SYMCHK: sqlservr.exe FAILED – sqlservr.pdb mismatched or not found

    SYMCHK: FAILED files = 1
    SYMCHK: PASSED + IGNORED files = 0

    no matter what I try.

    Thanks

  3. I can confirm the same issue, debug symbols for SQL Server 2008 R2 SP2 cannot be downloaded at the moment.

  4. I get the same error as AA_Online and AFomchenko, with SQL 10.50.3720 (2008R2 Dev edition, 64bit):

    C:\Program Files\Microsoft SQL Server\MSSQL10_50.MSSQLSERVER\MSSQL\Binn>”C:\Program Files\Debugging Tools for Windows (x64)\symchk.exe” sqlservr.exe /s SRV*c:\symbols*http://msdl.microsoft.com/download/symbols

    SYMCHK: sqlservr.exe FAILED – sqlservr.pdb mismatched or not found

    SYMCHK: FAILED files = 1
    SYMCHK: PASSED + IGNORED files = 0

    C:\Program Files\Microsoft SQL Server\MSSQL10_50.MSSQLSERVER\MSSQL\Binn>

    I will install SP2 for SQL to get version 10.50.4000 and try again. Maybe pdb will be available for that build version.

  5. I did this but I am not getting all the correct symbol files. I did sqlos.dll, *.dll, sqlservr.exe and this is the result I get for IO_COMPLETION. I am really frustrated trying to figure what is causing this wait. What am I missing?

    0x0000000000976D94
    0x0000000000093F5F
    0x0000000000094195
    0x00000000000929B6
    0x000000000056CB6A
    0x000000000056CA1F
    0x000000000090F5A7
    GetIUMSForMsxml+967a81 [ @ 0+0x0
    0x000000000090F471
    0x000000000056CC80
    0x00000000000F3213
    0x00000000000F396A
    0x00000000000E4516
    0x00000000000F0296
    0x00000000000F039D
    0x00000000000D5E4D

    0x0000000000976D94
    0x0000000000093F5F
    0x0000000000094195
    0x00000000000929B6
    0x000000000056CB6A
    0x000000000056CA1F
    0x000000000056CBE0
    0x000000000056CC8B
    0x00000000000F3213
    0x00000000000F396A
    0x00000000000E4516
    0x00000000000F0296
    0x00000000000F039D
    0x00000000000D5E4D
    0x00000000000E5519
    0x00000000000D5E4D

    0x0000000000976D94
    0x0000000000093F5F
    0x0000000000094195
    0x00000000000929B6
    0x000000000056CB6A
    0x000000000056CA1F
    0x000000000056CBE0
    0x000000000090F3E2
    0x000000000056CC80
    0x00000000000F3213
    0x00000000000F396A
    0x00000000000E4516
    0x00000000000F0296
    0x00000000000F039D
    0x00000000000D5E4D
    0x00000000000E5519

    0x0000000000976D94
    0x0000000000093F5F
    0x0000000000094195
    0x00000000000929B6
    0x000000000056DB13
    0x000000000056D8E7
    0x00000000000F3293
    0x00000000000F391A
    0x00000000000E4531
    0x00000000000E7860
    0x00000000001569C7
    0x00000000000E5435
    0x00000000000E500B
    0x000000000015CDE1
    0x000000000015CC3A
    _____SQL______Process______Available+682c59 [ @ 0+0x0

    0x0000000000976D94
    0x0000000000093F5F
    0x0000000000094195
    0x00000000000929B6
    0x000000000090F8F5
    0x000000000065012F
    0x00000000000DA23B
    0x00000000000DA107
    0x00000000000D9C81
    0x00000000000D9DC9
    0x00000000000D9D42
    0x00000000000E7860
    0x00000000001569C7
    0x00000000000E5435
    0x00000000000E50D8
    0x000000000015CDE1

    1. Looks like you didn’t copy them into the correct directory, or didn’t turn on the trace flag. Worst case is you might need to bounce SQL Server. Which version are you using?

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