Fix runtime version detection for netstandard2.0 on .NET Framework#196
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Fix runtime version detection for netstandard2.0 on .NET Framework#196
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) When the netstandard2.0 build of Elastic.Transport is loaded by a .NET Framework host (e.g. 4.7.2), the `#if !NETFRAMEWORK` code path is taken and `GetNetCoreVersion()` is called instead of `GetFullFrameworkRuntime()`. All detection strategies in `GetNetCoreVersion` fail on .NET Framework: - `Environment.Version.Major` is 4 (not >= 5) - `TargetFrameworkAttribute.FrameworkName` is `.NETFramework,Version=v4.7.2` which doesn't match the `.NETCoreApp,Version=v` prefix - `DOTNET_RUNNING_IN_CONTAINER` env var is not set This caused two problems: 1. On older versions (pre-8f2386d), the returned null was passed to `SemVersion.TryParse` which called `Regex.Match(null)`, throwing an `ArgumentNullException` on client initialization. 2. After the null guard added in 8f2386d, the version silently resolves to "0.0.0" instead of the actual framework version, producing incorrect `net=` values in the metadata telemetry header. This commit adds a fallback in `GetNetCoreVersion` that detects .NET Framework from `RuntimeInformation.FrameworkDescription` (which reports e.g. ".NET Framework 4.8.4614.0") and extracts a semver-compatible major.minor.0 version string. This only activates when all other detection methods have already failed, so existing code paths for .NET Core/.NET 5+ are unaffected. Closes #192 Co-authored-by: Cursor <cursoragent@cursor.com>
flobernd
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Feb 23, 2026
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Thank you! That was on my TODO for way too long already.
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Summary
Fixes #192
GetNetCoreVersion()that detects .NET Framework fromRuntimeInformation.FrameworkDescriptionwhen thenetstandard2.0build is loaded by a .NET Framework hostmajor.minor.0version string (e.g."4.8.0"from".NET Framework 4.8.4614.0")Background
When the
netstandard2.0build runs on .NET Framework (e.g. 4.7.2), the#if !NETFRAMEWORKcode path is taken andGetNetCoreVersion()is called instead ofGetFullFrameworkRuntime(). All detection strategies fail:Environment.Version.Majoris 4 (not >= 5)TargetFrameworkAttribute.FrameworkNameis.NETFramework,Version=v4.7.2— doesn't match the.NETCoreApp,Version=vprefixDOTNET_RUNNING_IN_CONTAINERenv var is not setThis caused two issues:
nullwas passed toSemVersion.TryParse→Regex.Match(null)→ArgumentNullExceptionon client initializationEmpty(0.0.0), producing incorrectnet=0.0.0in the metadata telemetry headerMade with Cursor