large-functions.md

Troubleshooting large functions

You may see an error about generated functions being too large. This is because when deploying your site it is packaged into a zipfile, which is limited by AWS to 50MB in size. There are two possible causes for this, each with its own solution. The list of largest files shown in the build logs will help you see what the cause is.

• Large dependencies This is the most common cause of the problem. Some node modules are very large, mostly those that include native modules. Examples include electron and chromium. The function bundler is usually able to find out which modules are actually used by your code, but sometimes it will incorrectly include unneeded modules. If this is the case, you can either remove the module from your dependencies if you installed it yourself, or exclude it manually by adding something like this to your netlify.toml, changing the value according to the problematic module. The ! at the beginning of the module path indicates that it should be excluded:

  [functions]
  included_files = ["!node_modules/a-large-module/**/*"]

  If you do need large modules at runtime (e.g. if you are running Puppeteer in a Next API route), consider changing to a Netlify function which will have less overhead than the equivalent Next.js function.

• Large numbers of pre-rendered pages If you have a very large number of pre-rendered pages, these can take up a lot of space in the function. There are two approaches to fixing this. One is to consider deferring the building of the pages. If you return fallback: "blocking" from getStaticPaths the rendering will be deferred until the first user requests the page. This is a good choice for low-traffic pages. It reduces build and deploy time, and can make your bundle a lot smaller.