spring-projects/spring-ai · error · java.lang.IllegalArgumentException

Unknown HarmBlockThreshold:

Error message

Unknown HarmBlockThreshold: 

What it means

mapToGenAiHarmBlockThreshold converts GoogleGenAiSafetySetting.HarmBlockThreshold enums to genai SDK thresholds; the default branch throws IllegalArgumentException for any value the switch does not map. It means a threshold value outside the supported set reached the mapper.

Source

Thrown at models/spring-ai-google-genai/src/main/java/org/springframework/ai/google/genai/GoogleGenAiChatModel.java:849

		};
	}

	private static com.google.genai.types.HarmBlockThreshold mapToGenAiHarmBlockThreshold(
			GoogleGenAiSafetySetting.HarmBlockThreshold threshold) {
		return switch (threshold) {
			case HARM_BLOCK_THRESHOLD_UNSPECIFIED -> new com.google.genai.types.HarmBlockThreshold(
					com.google.genai.types.HarmBlockThreshold.Known.HARM_BLOCK_THRESHOLD_UNSPECIFIED);
			case BLOCK_LOW_AND_ABOVE -> new com.google.genai.types.HarmBlockThreshold(
					com.google.genai.types.HarmBlockThreshold.Known.BLOCK_LOW_AND_ABOVE);
			case BLOCK_MEDIUM_AND_ABOVE -> new com.google.genai.types.HarmBlockThreshold(
					com.google.genai.types.HarmBlockThreshold.Known.BLOCK_MEDIUM_AND_ABOVE);
			case BLOCK_ONLY_HIGH -> new com.google.genai.types.HarmBlockThreshold(
					com.google.genai.types.HarmBlockThreshold.Known.BLOCK_ONLY_HIGH);
			case BLOCK_NONE -> new com.google.genai.types.HarmBlockThreshold(
					com.google.genai.types.HarmBlockThreshold.Known.BLOCK_NONE);
			case OFF ->
				new com.google.genai.types.HarmBlockThreshold(com.google.genai.types.HarmBlockThreshold.Known.OFF);
			default -> throw new IllegalArgumentException("Unknown HarmBlockThreshold: " + threshold);
		};
	}

	private static ThinkingLevel mapToGenAiThinkingLevel(GoogleGenAiThinkingLevel level) {
		return switch (level) {
			case THINKING_LEVEL_UNSPECIFIED -> new ThinkingLevel(ThinkingLevel.Known.THINKING_LEVEL_UNSPECIFIED);
			case MINIMAL -> new ThinkingLevel(ThinkingLevel.Known.MINIMAL);
			case LOW -> new ThinkingLevel(ThinkingLevel.Known.LOW);
			case MEDIUM -> new ThinkingLevel(ThinkingLevel.Known.MEDIUM);
			case HIGH -> new ThinkingLevel(ThinkingLevel.Known.HIGH);
		};
	}

	private static FunctionCallingConfigMode mapToFunctionCallingConfigMode(
			GoogleGenAiChatOptions.ToolChoice.Mode mode) {
		return switch (mode) {
			case AUTO -> new FunctionCallingConfigMode(FunctionCallingConfigMode.Known.AUTO);
			case ANY -> new FunctionCallingConfigMode(FunctionCallingConfigMode.Known.ANY);

View on GitHub (pinned to 98a7beda4f)

Solutions

1. Use only mapped values such as BLOCK_ONLY_HIGH, BLOCK_NONE, OFF and the other cases the switch handles.
2. Check the exception message for the offending threshold value and fix your safety configuration.
3. Update the library or the mapper if a newly introduced enum constant is missing.
4. Parse config-driven thresholds defensively against the supported enum set.

Example fix

// before
new GoogleGenAiSafetySetting(category, HarmBlockThreshold.HARM_THRESHOLD_UNSPECIFIED);
// after
new GoogleGenAiSafetySetting(category, HarmBlockThreshold.BLOCK_ONLY_HIGH);

Set<HarmBlockThreshold> allowed = Set.of(BLOCK_NONE, BLOCK_ONLY_HIGH, OFF /* plus other mapped cases */);
if (!allowed.contains(threshold)) throw new IllegalArgumentException("unsupported: " + threshold);

boolean isMapped(HarmBlockThreshold t) { return EnumSet.of(BLOCK_NONE, BLOCK_ONLY_HIGH, OFF).contains(t); }

try { applySafety(settings); } catch (IllegalArgumentException e) { if (e.getMessage().startsWith("Unknown HarmBlockThreshold")) fixConfig(); else throw e; }

When it happens

Trigger: Configuring a safety setting with a HarmBlockThreshold constant not handled by the switch (e.g. HARM_THRESHOLD_UNSPECIFIED or a new constant) when constructing Gemini safety settings.

Common situations: Version drift where the enum gained new constants not yet mapped; building thresholds dynamically from config strings; copying thresholds from Vertex/other SDKs with different names.

Understand the failure class

Background: Invalid enum value errors: "Unknown type", "Invalid scope", "must be one of" — when a string is not on the library's allowed list — this error's family across 23 libraries.

Related errors

• Unknown HarmCategory:
• Incomplete Google GenAI configuration: Provide 'api-key' for
• Gemini doesn't support message type:
• Failed to generate content
• ThinkingLevel.%s is not supported for model '%s'. This model

AI-assisted analysis of spring-projects/spring-ai@98a7beda4f (2026-09-11). Data as JSON: /api/errors/dffff49c3d24c564. Report an issue: GitHub.