vercel/ai · error · APICallError

SSE stream ended without a data event

Error message

SSE stream ended without a data event

What it means

Error "SSE stream ended without a data event" thrown in vercel/ai.

Source

Thrown at packages/gateway/src/gateway-video-model.ts:100

            throw new APICallError({
              message: 'SSE response body is empty',
              url,
              requestBodyValues,
              statusCode: response.status,
            });
          }

          const eventStream = parseJsonEventStream({
            stream: response.body,
            schema: gatewayVideoEventSchema,
          });

          const reader = eventStream.getReader();
          const { done, value: parseResult } = await reader.read();
          reader.releaseLock();

          if (done || !parseResult) {
            throw new APICallError({
              message: 'SSE stream ended without a data event',
              url,
              requestBodyValues,
              statusCode: response.status,
            });
          }

          if (!parseResult.success) {
            throw new APICallError({
              message: 'Failed to parse video SSE event',
              cause: parseResult.error,
              url,
              requestBodyValues,
              statusCode: response.status,
            });
          }

          const event = parseResult.value;

View on GitHub (pinned to 69428b1f8b)

When it happens

Trigger: Thrown at packages/gateway/src/gateway-video-model.ts:100 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of vercel/ai@69428b1f8b (2026-08-30). Data as JSON: /api/errors/8580198531afc83d. Report an issue: GitHub.