Next.js 16.2.6 breaks Nextjs image optimizer for local public images

[dannysteenman]

Problem

After upgrading a SST sst.aws.Nextjs site from Next.js 16.2.4 to 16.2.6, optimized images served through /_next/image started returning HTTP 500 in production. The same source images are still reachable directly from the public asset path.

Example behavior:

• https://example.com/images/landing/services/aws-partner-network-badge.png -> 200
• https://example.com/_next/image?url=%2Fimages%2Flanding%2Fservices%2Faws-partner-network-badge.png&w=640&q=75 -> 500

Rolling back and pinning next and @next/third-parties to 16.2.4 fixes the issue immediately after redeploy.

Environment

• SST: 4.13.1
• Construct: sst.aws.Nextjs
• Next.js broken version: 16.2.6
• Next.js working version: 16.2.4
• Runtime in sst.config.ts: nodejs24.x
• Image optimization configured:

imageOptimization: {
  memory: '1792 MB',
},
server: {
  architecture: 'arm64',
  memory: '1792 MB',
  runtime: nodeRuntime,
},

Lambda logs

The SST image optimizer Lambda logs this for local public images:

ERROR upstream image response failed for /images/logos/cloudburn.png TypeError: s is not a function
    at Dye (file:///var/task/index.mjs:44:67054)
    at iPe (file:///var/task/index.mjs:102:60148)
    at oPe (file:///var/task/index.mjs:102:60971)
    at BufferedInvokeProcessor.handler (file:///var/task/index.mjs:44:83852)
    at async BufferedInvokeProcessor.processInvoke (file:///var/runtime/index.mjs:1092:22)

ERROR Failed to optimize image Ft [Error]: "url" parameter is valid but upstream response is invalid
    at Dye (file:///var/task/index.mjs:44:68211)
    at iPe (file:///var/task/index.mjs:102:60148)
    at oPe (file:///var/task/index.mjs:102:60971)
    at BufferedInvokeProcessor.handler (file:///var/task/index.mjs:44:83852)
    at async BufferedInvokeProcessor.processInvoke (file:///var/runtime/index.mjs:1092:22) {
  statusCode: 500
}

Likely cause

Next.js changed the internal fetchInternalImage function signature between 16.2.4 and 16.2.6.

In next@16.2.4:

async function fetchInternalImage(href, _req, _res, handleRequest) {

In next@16.2.6:

async function fetchInternalImage(href, _req, _res, maximumResponseBody, handleRequest) {

The error looks consistent with SST/OpenNext still calling the old 4-argument shape. If so, the real handleRequest function is passed as maximumResponseBody, and handleRequest becomes undefined, producing the minified TypeError: s is not a function when the image optimizer tries to fetch a local public image.

Workaround

Pin Next packages to 16.2.4:

{
  "dependencies": {
    "@next/third-parties": "16.2.4",
    "next": "16.2.4"
  }
}

After redeploying with 16.2.4, the /_next/image URLs work again.

Expected behavior

SST's Next.js image optimizer should support the Next.js 16.2.6 internal image optimizer signature, or pin/guard incompatible Next.js versions with a clear error.

[sam-jg]

Can also replicate this issue, was driving me nuts trying to debug.

[redenvci]

fixed by pinning openNextVersion to latest in Nextjs Component
openNextVersion: "4.0.2",

[damien-monni]

Is there any fix planned for that?