INTERNAL_FUNCTION_INVOCATION_TIMEOUT

The INTERNAL_FUNCTION_INVOCATION_TIMEOUT error occurs when a function invocation takes longer than the allowed execution time. This could be due to an error within the function itself, a slow network call, or an issue with the environment in which the function is running.

To troubleshoot this error, follow these steps:

1. The function is taking too long to process a request: Ensure that any API or database requests you make in your function respond within the Vercel Function maximum duration limit applicable to your plan. If you require a longer execution, consider enabling Fluid compute, which provides significantly longer durations and optimized performance for extended workloads.
2. The function isn't returning a response: The function must return an HTTP response, even if that response is an error. If no response is returned, the function will time out
3. You have an infinite loop within your function: Check that your function is not making an infinite loop at any stage of execution
4. Upstream errors: Check that any external API or database that you are attempting to call doesn't have any errors
5. A common cause for this issue is when the application contains an unhandled exception. Check the application logs, which can be found at the host URL under the /_logs path, for example:

https://my-deployment-my-username.vercel.app/_logs

For more information on Vercel Functions timeouts, see What can I do about Vercel Serverless Functions timing out?