earendil-works/pi · error

Anthropic stream ended without a stop reason

Error message

Anthropic stream ended without a stop reason

What it means

Error "Anthropic stream ended without a stop reason" thrown in earendil-works/pi.

Source

Thrown at packages/ai/src/api/anthropic-messages.ts:776

						const thinkingTokens = (event.usage as { output_tokens_details?: { thinking_tokens?: number } })
							.output_tokens_details?.thinking_tokens;
						if (thinkingTokens != null) {
							output.usage.reasoning = thinkingTokens;
						}
					}
					// Anthropic doesn't provide total_tokens, compute from components
					output.usage.totalTokens =
						output.usage.input + output.usage.output + output.usage.cacheRead + output.usage.cacheWrite;
					calculateCost(usageModel, output.usage);
				}
			}

			if (options?.signal?.aborted) {
				throw new Error("Request was aborted");
			}

			if (output.stopReason === "pending") {
				throw new Error("Anthropic stream ended without a stop reason");
			}
			if (output.stopReason === "aborted" || output.stopReason === "error") {
				throw new Error(output.errorMessage || "An unknown error occurred");
			}

			stream.push({ type: "done", reason: output.stopReason, message: output });
			stream.end();
		} catch (error) {
			for (const block of output.content) {
				delete (block as { index?: number }).index;
				// partialJson is only a streaming scratch buffer; never persist it.
				delete (block as { partialJson?: string }).partialJson;
			}
			output.stopReason = options?.signal?.aborted ? "aborted" : "error";
			output.errorMessage = error instanceof Error ? error.message : JSON.stringify(error);
			stream.push({ type: "error", reason: output.stopReason, error: output });
			stream.end();
		}

View on GitHub (pinned to 4af9d21d3b)

Solutions

1. Retry; treat the stream as truncated and inspect prior events for an error payload.

When it happens

Trigger: Thrown at packages/ai/src/api/anthropic-messages.ts:776 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of earendil-works/pi@4af9d21d3b (2026-08-24). Data as JSON: /api/errors/d66a2757ee752286. Report an issue: GitHub.