Test failure: System.Security.Cryptography.EcDiffieHellman.Tests.ECDhKeyFileTests_Default.ReadWriteNistP256ExplicitEncryptedPkcs8

**Failed in:** [runtime-coreclr libraries-pgo 20260627.1](https://dev.azure.com/dnceng-public/cbb18261-c48f-4abb-8651-8cdcb5474649/_build/results?buildId=1484392)

**Failed tests:**
```
net11.0-linux-Release-x64-syntheticpgo_blend-AzureLinux.3.Amd64.Open
- System.Security.Cryptography.EcDiffieHellman.Tests.ECDhKeyFileTests_Default.ReadWriteNistP256ExplicitEncryptedPkcs8
- System.Security.Cryptography.EcDiffieHellman.Tests.ECDhKeyFileTests_Default.ReadWriteNistP256ExplicitECPrivateKey_LimitedPrivate
- System.Security.Cryptography.EcDiffieHellman.Tests.ECDhKeyFileTests_Default.ReadWriteNistP256ExplicitECPrivateKey
- System.Security.Cryptography.EcDiffieHellman.Tests.ECDhKeyFileTests_Default.ReadWriteNistP256ExplicitEncryptedPkcs8_LimitedPrivate
- System.Security.Cryptography.EcDiffieHellman.Tests.ECDhKeyFileTests_Default.ReadWriteNistP256ExplicitSubjectPublicKeyInfo
- System.Security.Cryptography.EcDiffieHellman.Tests.ECDhKeyFileTests_Default.ReadWriteNistP256ExplicitPkcs8_LimitedPrivate
- System.Security.Cryptography.EcDiffieHellman.Tests.ECDhKeyFileTests_Default.ReadWriteNistP256ExplicitPkcs8
- System.Security.Cryptography.EcDsa.Tests.ECDsaKeyFileTests_Default.ReadWriteNistP256ExplicitPkcs8_LimitedPrivate
- System.Security.Cryptography.EcDsa.Tests.ECDsaKeyFileTests_Default.ReadWriteNistP256ExplicitSubjectPublicKeyInfo
- System.Security.Cryptography.EcDsa.Tests.ECDsaKeyFileTests_Default.ReadWriteNistP256ExplicitEncryptedPkcs8
- System.Security.Cryptography.EcDsa.Tests.ECDsaKeyFileTests_Default.ReadWriteNistP256ExplicitEncryptedPkcs8_LimitedPrivate
- System.Security.Cryptography.EcDsa.Tests.ECDsaKeyFileTests_Default.ReadWriteNistP256ExplicitPkcs8
- System.Security.Cryptography.EcDsa.Tests.ECDsaKeyFileTests_Default.ReadWriteNistP256ExplicitECPrivateKey
- System.Security.Cryptography.EcDsa.Tests.ECDsaKeyFileTests_Default.ReadWriteNistP256ExplicitECPrivateKey_LimitedPrivate
- System.Security.Cryptography.EcDsa.Tests.ECDsaKeyFileTests_OpenSsl.ReadWriteNistP256ExplicitECPrivateKey_LimitedPrivate
- System.Security.Cryptography.EcDsa.Tests.ECDsaKeyFileTests_OpenSsl.ReadWriteNistP256ExplicitPkcs8
- System.Security.Cryptography.EcDsa.Tests.ECDsaKeyFileTests_OpenSsl.ReadWriteNistP256ExplicitEncryptedPkcs8
- System.Security.Cryptography.EcDsa.Tests.ECDsaKeyFileTests_OpenSsl.ReadWriteNistP256ExplicitSubjectPublicKeyInfo
- System.Security.Cryptography.EcDsa.Tests.ECDsaKeyFileTests_OpenSsl.ReadWriteNistP256ExplicitECPrivateKey
- System.Security.Cryptography.EcDsa.Tests.ECDsaKeyFileTests_OpenSsl.ReadWriteNistP256ExplicitEncryptedPkcs8_LimitedPrivate
- System.Security.Cryptography.EcDsa.Tests.ECDsaKeyFileTests_OpenSsl.ReadWriteNistP256ExplicitPkcs8_LimitedPrivate
- System.Security.Cryptography.EcDiffieHellman.Tests.ECDhKeyFileTests_OpenSsl.ReadWriteNistP256ExplicitECPrivateKey_LimitedPrivate
- System.Security.Cryptography.EcDiffieHellman.Tests.ECDhKeyFileTests_OpenSsl.ReadWriteNistP256ExplicitSubjectPublicKeyInfo
- System.Security.Cryptography.EcDiffieHellman.Tests.ECDhKeyFileTests_OpenSsl.ReadWriteNistP256ExplicitPkcs8_LimitedPrivate
- System.Security.Cryptography.EcDiffieHellman.Tests.ECDhKeyFileTests_OpenSsl.ReadWriteNistP256ExplicitPkcs8
- System.Security.Cryptography.EcDiffieHellman.Tests.ECDhKeyFileTests_OpenSsl.ReadWriteNistP256ExplicitEncryptedPkcs8
- System.Security.Cryptography.EcDiffieHellman.Tests.ECDhKeyFileTests_OpenSsl.ReadWriteNistP256ExplicitEncryptedPkcs8_LimitedPrivate
- System.Security.Cryptography.EcDiffieHellman.Tests.ECDhKeyFileTests_OpenSsl.ReadWriteNistP256ExplicitECPrivateKey

```

**Error message:**
```
Assert.ThrowsAny() Failure: No exception was thrown
Expected: typeof(System.Exception)
```

**Stack trace:**
```
at System.Security.Cryptography.Tests.ECKeyFileTests`1.ReadWriteBase64EncryptedPkcs8(String base64EncryptedPkcs8, String password, PbeParameters pbe, ECParameters& expected, Boolean isSupported) in /_/src/libraries/Common/tests/System/Security/Cryptography/AlgorithmImplementations/EC/ECKeyFileTests.cs:line 1034
at System.Security.Cryptography.Tests.ECKeyFileTests`1.ReadWriteNistP256ExplicitEncryptedPkcs8() in /_/src/libraries/Common/tests/System/Security/Cryptography/AlgorithmImplementations/EC/ECKeyFileTests.cs:line 269
at System.RuntimeMethodHandle.InvokeMethod(ObjectHandleOnStack target, Void** arguments, ObjectHandleOnStack sig, BOOL isConstructor, ObjectHandleOnStack result)
at System.RuntimeMethodHandle.InvokeMethod(ObjectHandleOnStack target, Void** arguments, ObjectHandleOnStack sig, BOOL isConstructor, ObjectHandleOnStack result)
at System.Reflection.MethodBaseInvoker.InterpretedInvoke_Method(Object obj, IntPtr* args) in /_/src/coreclr/System.Private.CoreLib/src/System/Reflection/MethodBaseInvoker.CoreCLR.cs:line 37
at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture) in /_/src/libraries/System.Private.CoreLib/src/System/Reflection/RuntimeMethodInfo.cs:line 134
```

Start with src/libraries/Common/tests/System/Security/Cryptography/AlgorithmImplementations/EC/ECKeyFileTests.cs, especially ReadWriteNistP256ExplicitEncryptedPkcs8 at line 269 and ReadWriteBase64EncryptedPkcs8 at line 1034. Reproduce the listed Linux failures from build 1484392, then determine why the affected tests do not throw the expected exception; done means the affected ECDh and ECDsa tests pass with their intended assertions.

Written by the indexing model from the issue text.