Debugging stuck renders

If your render is stuck, proceed as follows:

Check for long delayRender() calls

If the delayRender() timeout is too big and does not resolve, a render may get stuck indefinitely without an error message.

This issue may be more confusing on Remotion Lambda, whose runtime also has a timeout.
If the delayRender() timeout is bigger than the Lambda function timeout, the Lambda function will first time out without the delayRender() call failing first, leading to no error message.

To debug the issue:

• Set the delayRender() timeout value to a smaller value, so that if it does not resolve, an error message is shown.
• Always use cancelRender() to handle any error that prevents you from calling continueRender().

Enable verbose logging

Enable verbose logging to see if there are any failures from the browser or other child processes.

Ensure Chrome Headless Shell is used

Newer Chrome versions may not work with Remotion anymore and cause a render to get stuck, because they have removed the Headless mode.
Instead, you need to migrate to the Chrome Headless Shell.

:::note This issue does not occur on Remotion Lambda. :::

Follow these best practices:

• Do not download Chrome from a Linux package manager.
• Do not set the --chrome-executable option and let Remotion download a compatible version of Chrome Headless Shell for you.
• Use npx remotion browser ensure to make sure a compatible versions of Chrome Headless Shell is ready before the first render.

Lambda: Are you reading the errors field?

If the overallProgress field is stuck on Lambda, ensure that you are:

• Reading the errors field to see if there are any errors.
• not further polling getRenderProgress() if the fatalErrorEncountered field is true.