diff --git a/Directory.Packages.props b/Directory.Packages.props
index b8b977b6f3..32d9133eac 100644
--- a/Directory.Packages.props
+++ b/Directory.Packages.props
@@ -15,7 +15,7 @@
     <PackageVersion Include="Microsoft.IdentityModel.Abstractions" Version="6.22.0" />
     <PackageVersion Include="Microsoft.Web.WebView2" Version="1.0.864.35" />
     <PackageVersion Include="System.ComponentModel.TypeConverter" Version="4.3.0" />
-    <PackageVersion Include="System.Diagnostics.DiagnosticSource" Version="7.0.2" />
+    <PackageVersion Include="System.Diagnostics.DiagnosticSource" Version="6.0.1" /> <!-- Should match Azure Functions runtime: https://github.com/AzureAD/microsoft-authentication-library-for-dotnet/issues/4456 -->
     <PackageVersion Include="System.IO.FileSystem.AccessControl" Version="5.0.0" />
     <PackageVersion Include="System.Net.NameResolution" Version="4.3.0" />
     <PackageVersion Include="System.Runtime.Serialization.Formatters" Version="4.3.0" />
diff --git a/src/client/Microsoft.Identity.Client/Platforms/Features/OpenTelemetry/OtelInstrumentation.cs b/src/client/Microsoft.Identity.Client/Platforms/Features/OpenTelemetry/OtelInstrumentation.cs
index 3593e2d7df..a0986b2d41 100644
--- a/src/client/Microsoft.Identity.Client/Platforms/Features/OpenTelemetry/OtelInstrumentation.cs
+++ b/src/client/Microsoft.Identity.Client/Platforms/Features/OpenTelemetry/OtelInstrumentation.cs
@@ -80,6 +80,12 @@ internal class OtelInstrumentation : IOtelInstrumentation
             unit: "ms",
             description: "Performance of token acquisition calls network latency"));
 
+        public OtelInstrumentation()
+        {
+            // Needed to fail fast if the runtime, like in-process Azure Functions, doesn't support OpenTelemetry 
+            _ = Meter.Version;
+        }
+
         // Aggregates the successful requests based on token source and cache refresh reason.
         void IOtelInstrumentation.LogSuccessMetrics(
             string platform,
diff --git a/src/client/Microsoft.Identity.Client/PlatformsCommon/Shared/AbstractPlatformProxy.cs b/src/client/Microsoft.Identity.Client/PlatformsCommon/Shared/AbstractPlatformProxy.cs
index 85c8a22ce8..1d6d69a8fb 100644
--- a/src/client/Microsoft.Identity.Client/PlatformsCommon/Shared/AbstractPlatformProxy.cs
+++ b/src/client/Microsoft.Identity.Client/PlatformsCommon/Shared/AbstractPlatformProxy.cs
@@ -2,7 +2,7 @@
 // Licensed under the MIT License.
 
 using System;
-using System.Security.Cryptography.X509Certificates;
+using System.IO;
 using System.Threading.Tasks;
 using Microsoft.Identity.Client.AuthScheme.PoP;
 using Microsoft.Identity.Client.Cache;
@@ -55,7 +55,15 @@ protected AbstractPlatformProxy(ILoggerAdapter logger)
         private IOtelInstrumentation InternalGetOtelInstrumentation()
         {
 #if SUPPORTS_OTEL
-            return new OtelInstrumentation();
+            try
+            {
+                return new OtelInstrumentation();
+            } catch (FileNotFoundException ex) 
+            {
+                // Can happen in in-process Azure Functions: https://github.com/AzureAD/microsoft-authentication-library-for-dotnet/issues/4456
+                Logger.Warning("Failed instantiating OpenTelemetry instrumentation. Exception: " + ex.Message);
+                return new NullOtelInstrumentation();
+            }
 #else
             return new NullOtelInstrumentation();
 #endif