diff --git a/sdk/@launchdarkly/observability-dotnet/src/LaunchDarkly.Observability/Otel/CommonOtelOptions.cs b/sdk/@launchdarkly/observability-dotnet/src/LaunchDarkly.Observability/Otel/CommonOtelOptions.cs
index 3f765ada2..37cc01987 100644
--- a/sdk/@launchdarkly/observability-dotnet/src/LaunchDarkly.Observability/Otel/CommonOtelOptions.cs
+++ b/sdk/@launchdarkly/observability-dotnet/src/LaunchDarkly.Observability/Otel/CommonOtelOptions.cs
@@ -4,10 +4,8 @@
 using System.Threading.Tasks;
 using LaunchDarkly.Observability.Logging;
 using LaunchDarkly.Observability.Sampling;
-using LaunchDarkly.Sdk.Internal.Concurrent;
 using OpenTelemetry;
 using OpenTelemetry.Exporter;
-using OpenTelemetry.Logs;
 using OpenTelemetry.Metrics;
 using OpenTelemetry.Resources;
 using OpenTelemetry.Trace;
diff --git a/sdk/@launchdarkly/observability-dotnet/test/LaunchDarkly.Observability.Tests/CustomSamplerTests.cs b/sdk/@launchdarkly/observability-dotnet/test/LaunchDarkly.Observability.Tests/CustomSamplerTests.cs
index f41ef0adb..fbfbeef2e 100644
--- a/sdk/@launchdarkly/observability-dotnet/test/LaunchDarkly.Observability.Tests/CustomSamplerTests.cs
+++ b/sdk/@launchdarkly/observability-dotnet/test/LaunchDarkly.Observability.Tests/CustomSamplerTests.cs
@@ -241,8 +241,10 @@ private LogLevel SeverityTextToLogLevel(string severityText)
                 case null:
                     return LogLevel.Information;
                 default:
-                    // Unsupported in this test suite.
-                    throw new ArgumentOutOfRangeException(nameof(severityText), severityText, null);
+                    // Log records cannot be made without a level, but in some languages they can, so we
+                    // use "Information" for a missing level in the test suite.
+                    // We cannot use "None" because the open telemetry logger is hard-coded to discard "None".
+                    return LogLevel.Information;
             }
         }
 
diff --git a/sdk/@launchdarkly/observability-dotnet/test/LaunchDarkly.Observability.Tests/log-test-scenarios.json b/sdk/@launchdarkly/observability-dotnet/test/LaunchDarkly.Observability.Tests/log-test-scenarios.json
index 97ec818f6..38efec42e 100644
--- a/sdk/@launchdarkly/observability-dotnet/test/LaunchDarkly.Observability.Tests/log-test-scenarios.json
+++ b/sdk/@launchdarkly/observability-dotnet/test/LaunchDarkly.Observability.Tests/log-test-scenarios.json
@@ -388,5 +388,102 @@
 				}
 			}
 		]
+	},
+	{
+		"description": "Should not match an empty log when message and severity are defined",
+		"samplingConfig": {
+			"logs": [
+				{
+					"message": {
+						"regexValue": "Database connection .*"
+					},
+					"severityText": {
+						"matchValue": "error"
+					},
+					"samplingRatio": 90
+				}
+			]
+		},
+		"inputLog": {},
+		"samplerFunctionCases": [
+			{
+				"type": "always",
+				"expected_result": {
+					"sample": true
+				}
+			},
+			{
+				"type": "never",
+				"expected_result": {
+					"sample": true
+				}
+			}
+		]
+	},
+	{
+		"description": "Should not match a log with a message when message and severity are defined",
+		"samplingConfig": {
+			"logs": [
+				{
+					"message": {
+						"regexValue": "Database connection .*"
+					},
+					"severityText": {
+						"matchValue": "error"
+					},
+					"samplingRatio": 90
+				}
+			]
+		},
+		"inputLog": {
+			"message": "Database connection failed: timeout"
+		},
+		"samplerFunctionCases": [
+			{
+				"type": "always",
+				"expected_result": {
+					"sample": true
+				}
+			},
+			{
+				"type": "never",
+				"expected_result": {
+					"sample": true
+				}
+			}
+		]
+	},
+	{
+		"description": "Should not match a log with only severity when message and severity are defined",
+		"samplingConfig": {
+			"logs": [
+				{
+					"message": {
+						"regexValue": "Database connection .*"
+					},
+					"severityText": {
+						"matchValue": "error"
+					},
+					"samplingRatio": 90
+				}
+			]
+		},
+		"inputLog": {
+			"severityText": "error"
+		},
+		"samplerFunctionCases": [
+			{
+				"type": "always",
+				"expected_result": {
+					"sample": true
+				}
+			},
+			{
+				"type": "never",
+				"expected_result": {
+					"sample": true
+				}
+			}
+		]
 	}
 ]
diff --git a/sdk/@launchdarkly/observability-python/ldobserve/_otel/_sampling/log-test-scenarios.json b/sdk/@launchdarkly/observability-python/ldobserve/_otel/_sampling/log-test-scenarios.json
index 28ea1dee0..dd0ea7611 100644
--- a/sdk/@launchdarkly/observability-python/ldobserve/_otel/_sampling/log-test-scenarios.json
+++ b/sdk/@launchdarkly/observability-python/ldobserve/_otel/_sampling/log-test-scenarios.json
@@ -388,5 +388,102 @@
 				}
 			}
 		]
+	},
+	{
+		"description": "Should not match an empty log when message and severity are defined",
+		"samplingConfig": {
+			"logs": [
+				{
+					"message": {
+						"regexValue": "Database connection .*"
+					},
+					"severityText": {
+						"matchValue": "error"
+					},
+					"samplingRatio": 90
+				}
+			]
+		},
+		"inputLog": {},
+		"samplerFunctionCases": [
+			{
+				"type": "always",
+				"expected_result": {
+					"sample": true
+				}
+			},
+			{
+				"type": "never",
+				"expected_result": {
+					"sample": true
+				}
+			}
+		]
+	},
+	{
+		"description": "Should not match a log with a message when message and severity are defined",
+		"samplingConfig": {
+			"logs": [
+				{
+					"message": {
+						"regexValue": "Database connection .*"
+					},
+					"severityText": {
+						"matchValue": "error"
+					},
+					"samplingRatio": 90
+				}
+			]
+		},
+		"inputLog": {
+			"message": "Database connection failed: timeout"
+		},
+		"samplerFunctionCases": [
+			{
+				"type": "always",
+				"expected_result": {
+					"sample": true
+				}
+			},
+			{
+				"type": "never",
+				"expected_result": {
+					"sample": true
+				}
+			}
+		]
+	},
+	{
+		"description": "Should not match a log with only severity when message and severity are defined",
+		"samplingConfig": {
+			"logs": [
+				{
+					"message": {
+						"regexValue": "Database connection .*"
+					},
+					"severityText": {
+						"matchValue": "error"
+					},
+					"samplingRatio": 90
+				}
+			]
+		},
+		"inputLog": {
+			"severityText": "error"
+		},
+		"samplerFunctionCases": [
+			{
+				"type": "always",
+				"expected_result": {
+					"sample": true
+				}
+			},
+			{
+				"type": "never",
+				"expected_result": {
+					"sample": true
+				}
+			}
+		]
 	}
 ]
diff --git a/sdk/@launchdarkly/observability-python/ldobserve/_otel/_sampling/test_custom_sampler.py b/sdk/@launchdarkly/observability-python/ldobserve/_otel/_sampling/test_custom_sampler.py
index 6070c199a..9b6297aa8 100644
--- a/sdk/@launchdarkly/observability-python/ldobserve/_otel/_sampling/test_custom_sampler.py
+++ b/sdk/@launchdarkly/observability-python/ldobserve/_otel/_sampling/test_custom_sampler.py
@@ -177,7 +177,7 @@ def run_span_scenarios():
             assert sampler.is_sampling_enabled() is True
             result = sampler.sample_span(span)
             assert result.sample == expected["sample"], desc
-            if expected["attributes"] is not None:
+            if "attributes" in expected and expected["attributes"] is not None:
                 assert result.attributes == expected["attributes"], desc
             else:
                 assert result.attributes is None or result.attributes == {}, desc
@@ -202,7 +202,7 @@ def run_log_scenarios():
             assert sampler.is_sampling_enabled() is True
             result = sampler.sample_log(log)
             assert result.sample == expected["sample"], desc
-            if expected["attributes"] is not None:
+            if "attributes" in expected and expected["attributes"] is not None:
                 assert result.attributes == expected["attributes"], desc
             else:
                 assert result.attributes is None or result.attributes == {}, desc