The "Invocation canceled by client" error indicates that the client disconnected before the function finished executing. Function Compute interrupts the execution and logs the error.
Error message
The following error appears in the request log:
FC Invoke End RequestId: 1-64263a4b-2cd7c98b677*********, Error: Invocation canceled by client (duration: 4912ms, maxMemoryUsage: 0.00MB)Cause
The client canceled the request before the function completed, which interrupts execution and produces the error.
Common triggers include:
-
The client-side request timeout is shorter than the function execution duration.
-
A user manually canceled the request (for example, by clicking Cancel Request in the Function Compute console or closing the browser tab).
-
An intermediary service (such as API Gateway) enforced a backend timeout shorter than the function execution duration.
Solution
Step 1: Check the execution duration
Extract the duration value from the error message to see how long the function ran before the client disconnected.
In the example above, duration: 4912ms means the function ran for approximately 5 seconds.
Step 2: Determine whether the duration is expected
Compare the duration against the expected execution time for your function:
-
Duration is expected -- The function ran as long as it should, but the client timed out too early. See Increase client-side timeout.
-
Duration is unexpected -- The function took longer than it should. See Reduce function execution time.
Increase client-side timeout
If the function execution duration is within expectations, the client timeout is too short. Adjust the timeout based on how you invoke the function:
SDK or API invocation
Set the client-side request timeout to a value greater than the configured function timeout.
Go example: Set the timeout through the Timeout property in http.Client. If you use context.Context to initiate the request, adjust the deadline or timeout of the context.
// Set the HTTP client timeout to 120 seconds
client := &http.Client{
Timeout: 120 * time.Second,
}Invocation through another service
If another Alibaba Cloud service (such as API Gateway) triggers the function, modify the backend timeout of that service.
API Gateway example: Adjust the backend timeout settings in the API Gateway console. For details, see Create an API.
Console invocation
When you invoke a function from the Function Compute console, do not click Cancel Request or close the browser tab before the function finishes executing.
Reduce function execution time
If the function takes longer than expected, examine your function logs to identify the bottleneck. The two most common causes are I/O latency and compute-intensive operations.
I/O operations
Network I/O is the primary cause of unexpected latency. Add logging before and after each external call (database queries, API requests, storage operations) to isolate the slow call.
import time, logging
start = time.time()
# Call to external service
response = external_service.query(params)
logging.info(f"External service call took {time.time() - start:.2f}s")Computing operations
CPU-intensive operations can also increase execution duration. If profiling confirms a compute bottleneck, increase the CPU specifications allocated to the function.