vercel · kodiakhq · Jun 24, 2023 · Jun 24, 2023 · Jun 24, 2023
diff --git a/docs/02-app/01-building-your-application/03-data-fetching/04-server-actions.mdx b/docs/02-app/01-building-your-application/03-data-fetching/04-server-actions.mdx
@@ -382,6 +382,21 @@ export default function ExampleClientComponent({ myAction }) {
 
 In both cases, the form is interactive before hydration occurs. Although Server Actions have the additional benefit of not relying on client JavaScript, you can still compose additional behavior with Client Actions where desired without sacrificing interactivity.
 
+### Size Limitation
+
+By default, the maximum size of the request body sent to an Server Action is 1MB. This prevents large amounts of data being sent to the server, which consumes a lot of server resource to parse.
+
+However, you can configure this limit using the **experimental** `serverActionsBodySizeLimit` option. It can take the number of bytes or any string format supported by bytes, for example `1000`, `'500kb'` or `'3mb'`.
+
+```js filename="next.config.js"
+module.exports = {
+  experimental: {
+    serverActions: true,
+    serverActionsBodySizeLimit: '2mb',
+  },
+}
+```
+
 ## Examples
 
 ### Usage with Client Components

diff --git a/packages/next/src/build/entries.ts b/packages/next/src/build/entries.ts
@@ -377,7 +377,8 @@ export function getEdgeServerEntry(opts: {
     middlewareConfig: Buffer.from(
       JSON.stringify(opts.middlewareConfig || {})
     ).toString('base64'),
-    serverActionsSizeLimit: opts.config.experimental.serverActionsSizeLimit,
+    serverActionsBodySizeLimit:
+      opts.config.experimental.serverActionsBodySizeLimit,
   }
 
   return {

diff --git a/packages/next/src/build/webpack/loaders/next-edge-ssr-loader/index.ts b/packages/next/src/build/webpack/loaders/next-edge-ssr-loader/index.ts
@@ -23,7 +23,7 @@ export type EdgeSSRLoaderQuery = {
   incrementalCacheHandlerPath?: string
   preferredRegion: string | string[] | undefined
   middlewareConfig: string
-  serverActionsSizeLimit?: SizeLimit
+  serverActionsBodySizeLimit?: SizeLimit
 }
 
 /*
@@ -57,7 +57,7 @@ const edgeSSRLoader: webpack.LoaderDefinitionFunction<EdgeSSRLoaderQuery> =
       incrementalCacheHandlerPath,
       preferredRegion,
       middlewareConfig: middlewareConfigBase64,
-      serverActionsSizeLimit,
+      serverActionsBodySizeLimit,
     } = this.getOptions()
 
     const middlewareConfig: MiddlewareConfig = JSON.parse(
@@ -177,10 +177,10 @@ const edgeSSRLoader: webpack.LoaderDefinitionFunction<EdgeSSRLoaderQuery> =
       reactLoadableManifest,
       clientReferenceManifest: ${isServerComponent} ? rscManifest : null,
       serverActionsManifest: ${isServerComponent} ? rscServerManifest : null,
-      serverActionsSizeLimit: ${isServerComponent} ? ${
-      typeof serverActionsSizeLimit === 'undefined'
+      serverActionsBodySizeLimit: ${isServerComponent} ? ${
+      typeof serverActionsBodySizeLimit === 'undefined'
         ? 'undefined'
-        : JSON.stringify(serverActionsSizeLimit)
+        : JSON.stringify(serverActionsBodySizeLimit)
     } : undefined,
       subresourceIntegrityManifest,
       config: ${stringifiedConfig},

diff --git a/packages/next/src/build/webpack/loaders/next-edge-ssr-loader/render.ts b/packages/next/src/build/webpack/loaders/next-edge-ssr-loader/render.ts
@@ -32,7 +32,7 @@ export function getRender({
   clientReferenceManifest,
   subresourceIntegrityManifest,
   serverActionsManifest,
-  serverActionsSizeLimit,
+  serverActionsBodySizeLimit,
   config,
   buildId,
   nextFontManifest,
@@ -53,7 +53,7 @@ export function getRender({
   subresourceIntegrityManifest?: Record<string, string>
   clientReferenceManifest?: ClientReferenceManifest
   serverActionsManifest: any
-  serverActionsSizeLimit?: SizeLimit
+  serverActionsBodySizeLimit?: SizeLimit
   appServerMod: any
   config: NextConfigComplete
   buildId: string
@@ -88,7 +88,7 @@ export function getRender({
         disableOptimizedLoading: true,
         clientReferenceManifest,
         serverActionsManifest,
-        serverActionsSizeLimit,
+        serverActionsBodySizeLimit,
       },
       renderToHTML,
       incrementalCacheHandler,

diff --git a/packages/next/src/build/webpack/plugins/flight-client-entry-plugin.ts b/packages/next/src/build/webpack/plugins/flight-client-entry-plugin.ts
@@ -37,7 +37,7 @@ interface Options {
   appDir: string
   isEdgeServer: boolean
   useServerActions: boolean
-  serverActionsSizeLimit?: SizeLimit
+  serverActionsBodySizeLimit?: SizeLimit
 }
 
 const PLUGIN_NAME = 'ClientEntryPlugin'
@@ -153,15 +153,15 @@ export class ClientReferenceEntryPlugin {
   appDir: string
   isEdgeServer: boolean
   useServerActions: boolean
-  serverActionsSizeLimit?: SizeLimit
+  serverActionsBodySizeLimit?: SizeLimit
   assetPrefix: string
 
   constructor(options: Options) {
     this.dev = options.dev
     this.appDir = options.appDir
     this.isEdgeServer = options.isEdgeServer
     this.useServerActions = options.useServerActions
-    this.serverActionsSizeLimit = options.serverActionsSizeLimit
+    this.serverActionsBodySizeLimit = options.serverActionsBodySizeLimit
     this.assetPrefix = !this.dev && !this.isEdgeServer ? '../' : ''
   }
 

diff --git a/packages/next/src/export/index.ts b/packages/next/src/export/index.ts
@@ -472,7 +472,8 @@ export default async function exportApp(
       largePageDataBytes: nextConfig.experimental.largePageDataBytes,
       serverComponents: options.hasAppDir,
       hasServerComponents: options.hasAppDir,
-      serverActionsSizeLimit: nextConfig.experimental.serverActionsSizeLimit,
+      serverActionsBodySizeLimit:
+        nextConfig.experimental.serverActionsBodySizeLimit,
       nextFontManifest: require(join(
         distDir,
         'server',

diff --git a/packages/next/src/server/app-render/action-handler.ts b/packages/next/src/server/app-render/action-handler.ts
@@ -6,6 +6,7 @@ import type {
 } from 'http'
 import type { WebNextRequest } from '../base-http/web'
 import type { SizeLimit } from '../../../types'
+import type { ApiError } from '../api-utils'
 
 import {
   ACTION,
@@ -246,7 +247,7 @@ export async function handleAction({
   generateFlight,
   staticGenerationStore,
   requestStore,
-  serverActionsSizeLimit,
+  serverActionsBodySizeLimit,
 }: {
   req: IncomingMessage
   res: ServerResponse
@@ -260,7 +261,7 @@ export async function handleAction({
   }) => Promise<RenderResult>
   staticGenerationStore: StaticGenerationStore
   requestStore: RequestStore
-  serverActionsSizeLimit?: SizeLimit
+  serverActionsBodySizeLimit?: SizeLimit
 }): Promise<undefined | RenderResult | 'not-found'> {
   let actionId = req.headers[ACTION.toLowerCase()] as string
   const contentType = req.headers['content-type']
@@ -376,8 +377,20 @@ export async function handleAction({
             const { parseBody } =
               require('../api-utils/node') as typeof import('../api-utils/node')
 
-            const actionData =
-              (await parseBody(req, serverActionsSizeLimit ?? '1mb')) || ''
+            let actionData
+            try {
+              actionData =
+                (await parseBody(req, serverActionsBodySizeLimit ?? '1mb')) ||
+                ''
+            } catch (e: any) {
+              if (e && (e as ApiError).statusCode === 413) {
+                // Exceeded the size limit
+                e.message =
+                  e.message +
+                  '\nTo configure the body size limit for Server Actions, see: https://nextjs.org/docs/app/building-your-application/data-fetching/server-actions#size-limitation'
+              }
+              throw e
+            }
 
             if (isURLEncodedAction) {
               const formData = formDataFromSearchQueryString(actionData)

diff --git a/packages/next/src/server/app-render/app-render.tsx b/packages/next/src/server/app-render/app-render.tsx
@@ -156,7 +156,7 @@ export async function renderToHTMLOrFlight(
     nextFontManifest,
     supportsDynamicHTML,
     nextConfigOutput,
-    serverActionsSizeLimit,
+    serverActionsBodySizeLimit,
   } = renderOpts
 
   const appUsingSizeAdjust = nextFontManifest?.appUsingSizeAdjust
@@ -1607,7 +1607,7 @@ export async function renderToHTMLOrFlight(
       generateFlight,
       staticGenerationStore,
       requestStore,
-      serverActionsSizeLimit,
+      serverActionsBodySizeLimit,
     })
 
     if (actionRequestResult === 'not-found') {

diff --git a/packages/next/src/server/app-render/types.ts b/packages/next/src/server/app-render/types.ts
@@ -146,7 +146,7 @@ export type RenderOptsPartial = {
     rawConfig?: boolean,
     silent?: boolean
   ) => Promise<NextConfigComplete>
-  serverActionsSizeLimit?: SizeLimit
+  serverActionsBodySizeLimit?: SizeLimit
 }
 
 export type RenderOpts = LoadComponentsReturnType & RenderOptsPartial
diff --git a/packages/next/src/server/base-server.ts b/packages/next/src/server/base-server.ts
@@ -255,7 +255,7 @@ export default abstract class Server<ServerOptions extends Options = Options> {
     supportsDynamicHTML?: boolean
     isBot?: boolean
     clientReferenceManifest?: ClientReferenceManifest
-    serverActionsSizeLimit?: SizeLimit
+    serverActionsBodySizeLimit?: SizeLimit
     serverActionsManifest?: any
     nextFontManifest?: NextFontManifest
     renderServerComponentData?: boolean
@@ -1651,8 +1651,8 @@ export default abstract class Server<ServerOptions extends Options = Options> {
               incrementalCache,
               isRevalidate: isSSG,
               originalPathname: components.ComponentMod.originalPathname,
-              serverActionsSizeLimit:
-                this.nextConfig.experimental.serverActionsSizeLimit,
+              serverActionsBodySizeLimit:
+                this.nextConfig.experimental.serverActionsBodySizeLimit,
             }
           : {}),
         isDataReq,

diff --git a/packages/next/src/server/config-schema.ts b/packages/next/src/server/config-schema.ts
@@ -304,7 +304,7 @@ const configSchema = {
         serverActions: {
           type: 'boolean',
         },
-        serverActionsSizeLimit: {
+        serverActionsBodySizeLimit: {
           oneOf: [
             {
               type: 'number',

diff --git a/packages/next/src/server/config-shared.ts b/packages/next/src/server/config-shared.ts
@@ -286,7 +286,7 @@ export interface ExperimentalConfig {
   /**
    * Allows adjusting body parser size limit for server actions.
    */
-  serverActionsSizeLimit?: SizeLimit
+  serverActionsBodySizeLimit?: SizeLimit
 }
 
 export type ExportPathMap = {

diff --git a/packages/next/src/server/config.ts b/packages/next/src/server/config.ts
@@ -416,9 +416,9 @@ function assignDefaults(
     result.output = 'standalone'
   }
 
-  if (typeof result.experimental?.serverActionsSizeLimit !== 'undefined') {
+  if (typeof result.experimental?.serverActionsBodySizeLimit !== 'undefined') {
     const value = parseInt(
-      result.experimental.serverActionsSizeLimit.toString()
+      result.experimental.serverActionsBodySizeLimit.toString()
     )
     if (isNaN(value) || value < 1) {
       throw new Error(

diff --git a/packages/next/src/server/render.tsx b/packages/next/src/server/render.tsx
@@ -261,7 +261,7 @@ export type RenderOptsPartial = {
   isBot?: boolean
   runtime?: ServerRuntime
   serverComponents?: boolean
-  serverActionsSizeLimit?: SizeLimit
+  serverActionsBodySizeLimit?: SizeLimit
   customServer?: boolean
   crossOrigin?: 'anonymous' | 'use-credentials' | '' | undefined
   images: ImageConfigComplete

diff --git a/test/e2e/app-dir/actions/app-action-size-limit-invalid.test.ts b/test/e2e/app-dir/actions/app-action-size-limit-invalid.test.ts
@@ -21,14 +21,14 @@ createNextDescribe(
       return
     }
 
-    it('should error if serverActionsSizeLimit config is a negative number', async function () {
+    it('should error if serverActionsBodySizeLimit config is a negative number', async function () {
       await next.patchFile(
         'next.config.js',
         `
       module.exports = {
         experimental: {
           serverActions: true,
-          serverActionsSizeLimit: -3000,
+          serverActionsBodySizeLimit: -3000,
         },
       }
       `
@@ -40,14 +40,14 @@ createNextDescribe(
       expect(next.cliOutput).toContain(CONFIG_ERROR)
     })
 
-    it('should error if serverActionsSizeLimit config is invalid', async function () {
+    it('should error if serverActionsBodySizeLimit config is invalid', async function () {
       await next.patchFile(
         'next.config.js',
         `
       module.exports = {
         experimental: {
           serverActions: true,
-          serverActionsSizeLimit: 'testmb',
+          serverActionsBodySizeLimit: 'testmb',
         },
       }
       `
@@ -59,14 +59,14 @@ createNextDescribe(
       expect(next.cliOutput).toContain(CONFIG_ERROR)
     })
 
-    it('should error if serverActionsSizeLimit config is a negative size', async function () {
+    it('should error if serverActionsBodySizeLimit config is a negative size', async function () {
       await next.patchFile(
         'next.config.js',
         `
       module.exports = {
         experimental: {
           serverActions: true,
-          serverActionsSizeLimit: '-3000mb',
+          serverActionsBodySizeLimit: '-3000mb',
         },
       }
       `
@@ -79,14 +79,14 @@ createNextDescribe(
     })
 
     if (!isNextDeploy) {
-      it('should respect the size set in serverActionsSizeLimit', async function () {
+      it('should respect the size set in serverActionsBodySizeLimit', async function () {
         await next.patchFile(
           'next.config.js',
           `
       module.exports = {
         experimental: {
           serverActions: true,
-          serverActionsSizeLimit: '1.5mb',
+          serverActionsBodySizeLimit: '1.5mb',
         },
       }
       `
@@ -112,9 +112,11 @@ createNextDescribe(
         await browser.elementByCss('#size-2mb').click()
 
         await check(() => {
-          return logs.some((log) =>
-            log.includes('Error: Body exceeded 1.5mb limit')
-          )
+          const fullLog = logs.join('')
+          return fullLog.includes('Error: Body exceeded 1.5mb limit') &&
+            fullLog.includes(
+              'To configure the body size limit for Server Actions, see'
+            )
             ? 'yes'
             : ''
         }, 'yes')