spring-projects/spring-ai · warning

Unknown message type: + type + , returning generic UserMessa

Error message

Unknown message type: + type + , returning generic UserMessage

What it means

In the message deserialization helper of RedisChatMemoryRepository, when a stored message's 'type' does not match any known kind, this warning is logged and the code degrades gracefully by returning a generic UserMessage built from the stored content and metadata. Unlike the get() path, the message is not dropped — but its original role (assistant/tool/system) is lost.

Source

Thrown at memory-repositories/spring-ai-model-chat-memory-repository-redis/src/main/java/org/springframework/ai/chat/memory/repository/redis/RedisChatMemoryRepository.java:920

				JsonArray responseArray = json.getAsJsonArray("toolResponses");
				for (JsonElement responseElement : responseArray) {
					JsonObject responseJson = responseElement.getAsJsonObject();

					String id = responseJson.has("id") ? responseJson.get("id").getAsString() : "";
					String name = responseJson.has("name") ? responseJson.get("name").getAsString() : "";
					String responseData = responseJson.has("responseData")
							? responseJson.get("responseData").getAsString() : "";

					toolResponses.add(new ToolResponseMessage.ToolResponse(id, name, responseData));
				}
			}

			return ToolResponseMessage.builder().responses(toolResponses).metadata(metadata).build();
		}

		// For unknown message types, return a generic UserMessage
		if (logger.isWarnEnabled()) {
			logger.warn("Unknown message type: " + type + ", returning generic UserMessage");
		}
		return UserMessage.builder().text(content).metadata(metadata).build();
	}

	private List<Media> parseMedia(JsonObject json) {
		List<Media> mediaList = new ArrayList<>();
		if (json.has("media") && json.get("media").isJsonArray()) {
			JsonArray mediaArray = json.getAsJsonArray("media");
			for (JsonElement mediaElement : mediaArray) {
				JsonObject mediaJson = mediaElement.getAsJsonObject();
				String mimeTypeString = mediaJson.has("mimeType") ? mediaJson.get("mimeType").getAsString() : null;

				if (mimeTypeString != null) {
					MimeType mimeType = MimeType.valueOf(mimeTypeString);
					Media.Builder mediaBuilder = Media.builder().mimeType(mimeType);

					if (mediaJson.has("id")) {
						mediaBuilder.id(mediaJson.get("id").getAsString());

View on GitHub (pinned to 98a7beda4f)

Solutions

1. Check the stored entry's 'type' value in Redis and correct it to a supported kind (user/assistant/system/tool)
2. Keep the application's Spring AI version consistent with the version that wrote the data
3. Migrate unknown-typed messages to the closest supported type before reading
4. Validate JSON written by any custom code sharing the keyspace
5. Accept the fallback only if losing the original role is harmless for your use case

Example fix

// before
// stored: {"type":"ToolResponseMessage", ...}  -> returned as generic UserMessage
// after
// stored: {"type":"tool", ...}  -> correctly rebuilt as ToolResponseMessage

String type = json.get("type").getAsString();
if (!Set.of("user","assistant","system","tool").contains(type)) {
    throw new IllegalStateException("Unreadable stored message type: " + type);
}

static boolean isSupportedMessageType(String type) {
    return type != null && switch (type.toLowerCase()) { case "user","assistant","system","tool" -> true; default -> false; };
}

Message m = repositoryMessage(obj);
if (m instanceof UserMessage um && expectedAssistant) { log.warn("message degraded to UserMessage; check stored type"); }

When it happens

Trigger: Stored Redis message JSON with a 'type' value the repository doesn't recognize, hit while rebuilding a single message (e.g. from last()/findByConversationId paths).

Common situations: Cross-version Spring AI data in Redis; externally written or hand-edited entries; custom message types persisted without a matching reader; corrupted type strings (case differences, whitespace).

Related errors

• Unknown message type: + type
• Error reserving atomic timestamps for conversation + convers
• Failed to decode Base64 data, storing as string
• Could not parse text search score: ${doc.getString("$score")
• unknown message type %s

AI-assisted analysis of spring-projects/spring-ai@98a7beda4f (2026-09-11). Data as JSON: /api/errors/42147313b5acfc69. Report an issue: GitHub.