1.19.5 doesn't capture traces from IIS

Describe the bug When I install datadog-dotnet-apm-1.19.5-x64.msi I no longer get any traces appearing in the UI. 1.19.4 works fine.

To Reproduce Steps to reproduce the behavior:

1. Install datadog-dotnet-apm-1.19.5-x64.msi
2. Access pages on IIS
3. Check Trace screen to see if anything appears.

Expected behavior Traces should be captured and sent to the UI.

Runtime environment (please complete the following information):

• Instrumentation mode: automatic
• Tracer version: 1.19.5
• OS: Windows 2016
• CLR: .NET Framework 4.7.1
• DD Agent: 7.16.0

Additional context

dotnet-profiler.log shows the profiler being activated

[w3wp.exe] 13560: [info] Datadog CLR Profiler 1.19.5 32-bit
[w3wp.exe] 13560: [info] Environment variables:
[w3wp.exe] 13560: [info]   DD_TRACE_ENABLED=
[w3wp.exe] 13560: [info]   DD_TRACE_DEBUG=
[w3wp.exe] 13560: [info]   DD_DUMP_ILREWRITE_ENABLED=
[w3wp.exe] 13560: [info]   DD_DOTNET_TRACER_HOME=C:\Program Files\Datadog\.NET Tracer\
[w3wp.exe] 13560: [info]   DD_INTEGRATIONS=C:\Program Files\Datadog\.NET Tracer\integrations.json
[w3wp.exe] 13560: [info]   DD_PROFILER_PROCESSES=
[w3wp.exe] 13560: [info]   DD_PROFILER_EXCLUDE_PROCESSES=
[w3wp.exe] 13560: [info]   DD_AGENT_HOST=
[w3wp.exe] 13560: [info]   DD_TRACE_AGENT_PORT=
[w3wp.exe] 13560: [info]   DD_ENV=
[w3wp.exe] 13560: [info]   DD_SERVICE=
[w3wp.exe] 13560: [info]   DD_VERSION=
[w3wp.exe] 13560: [info]   DD_DISABLED_INTEGRATIONS=
[w3wp.exe] 13560: [info]   DD_CLR_DISABLE_OPTIMIZATIONS=
[w3wp.exe] 13560: [info]   DD_TRACE_DOMAIN_NEUTRAL_INSTRUMENTATION=
[w3wp.exe] 13560: [info]   DD_TRACE_NETSTANDARD_ENABLED=
[w3wp.exe] 13560: [info]   DD_AZURE_APP_SERVICES=
[w3wp.exe] 13560: [info]   APP_POOL_ID=CTN
[w3wp.exe] 13560: [info]   DOTNET_CLI_TELEMETRY_PROFILE=
[w3wp.exe] 13560: [info] Profiler attached.
[w3wp.exe] 13560: [info] JITCompilationStarted: Startup hook registered in function_id=140728718189472 token=100688371 name=System.Web.Compilation.BuildManager.InvokePreStartInitMethods(), assembly_name=System.Web app_domain_id=140730323304160 domain_neutral=1
[w3wp.exe] 13560: [info] ModuleLoadFinished: Datadog.Trace.ClrProfiler.Managed.Loader loaded into AppDomain 2008737549424 /LM/W3SVC/1/ROOT-1-132484404311801966
[w3wp.exe] 13560: [info] AssemblyLoadFinished: Datadog.Trace.ClrProfiler.Managed v1.19.5 matched profiler version v1.19.5
[w3wp.exe] 13560: [info] AssemblyLoadFinished: Datadog.Trace.ClrProfiler.Managed was loaded domain-neutral

trace-agent.log reports

2020-10-29 10:48:35 GMT | TRACE | INFO | (pkg/trace/info/stats.go:108 in LogStats) | [lang:.NET lang_version:4.7.1 interpreter:.NET Framework tracer_version:1.19.5.0] -> traces received: 0, traces filtered: 0, traces amount: 1 bytes, events extracted: 0, events sampled: 0
2020-10-29 10:50:55 GMT | TRACE | INFO | (pkg/trace/info/stats.go:101 in LogStats) | No data received
2020-10-29 10:51:55 GMT | TRACE | INFO | (pkg/trace/info/stats.go:101 in LogStats) | No data received

but there is traffic to IIS at this time

2020-10-29 10:51:28 W3SVC1 GET /heartbeat.aspx - 80 - Mozilla/5.0+(Windows+NT;+Windows+NT+10.0;+en-GB)+WindowsPowerShell/5.1.18362.1110 - 200 0 0 611 158 11 -
2020-10-29 10:51:28 W3SVC1 GET /heartbeat.aspx - 80 - Mozilla/5.0+(Windows+NT;+Windows+NT+10.0;+en-GB)+WindowsPowerShell/5.1.18362.1110 - 200 0 0 611 158 0 -

[rlaveycal]

It’s the runtimeVersion4.0 setting in the preCondition. There’s a typo - it should be runtimeVersionv4.0 (a v before the 4)

[kevingosse]

For customers finding this issue: the fix will be included in 1.19.7.

Until it’s available, you can also run this command from an administrator prompt to fix the configuration:

%systemroot%\system32\inetsrv\appcmd.exe set config /section:system.webServer/modules /[name='DatadogTracingModule'].preCondition:managedHandler,runtimeVersionv4.0