gatsbyjs/gatsby · error · Error

"app" chunk not found

Error message

"app" chunk not found

What it means

In optimizeChunks the plugin scans compilation.chunks for the chunk named 'app' to attach dangling CSS modules; not finding it means the expected app entry/chunk was absent at that hook — a build-internal invariant, often from customized entries or a changed Gatsby webpack setup.

Source

Thrown at packages/gatsby/src/utils/webpack/plugins/partial-hydration.ts:432

        normalModuleFactory.hooks.parser
          .for(`javascript/esm`)
          .tap(this.name, parserCallback)
        normalModuleFactory.hooks.parser
          .for(`javascript/dynamic`)
          .tap(this.name, parserCallback)

        // add dangling css modules to the app entry
        compilation.hooks.optimizeChunks.tap(this.name, () => {
          let appChunk: webpack.Chunk | null = null
          for (const chunk of compilation.chunks) {
            if (chunk.name === `app`) {
              appChunk = chunk
              break
            }
          }

          if (!appChunk) {
            throw new Error(`"app" chunk not found`)
          }

          const modulesToInsertIntoApp: Array<webpack.Module> = []

          for (const cssModule of this._collectedCssModules) {
            const usedInChunks =
              compilation.chunkGraph.getModuleChunksIterable(cssModule)

            let isInAnyChunk = false

            for (const _ of usedInChunks) {
              isInAnyChunk = true
              break
            }
            if (!isInAnyChunk) {
              modulesToInsertIntoApp.push(cssModule)
            }
          }

View on GitHub (pinned to e85d62f177)

Solutions

1. Avoid webpack config changes that rename or remove the 'app' entry
2. Update Gatsby to a version with partial-hydration chunk fixes
3. Disable partial hydration if not needed

When it happens

Trigger: Thrown at packages/gatsby/src/utils/webpack/plugins/partial-hydration.ts:432 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of gatsbyjs/gatsby@e85d62f177 (2026-08-26). Data as JSON: /api/errors/06e25f478cb99fc0. Report an issue: GitHub.