{"record":{"id":"08850e068eb45660","repo":"vercel/next.js","slug":"experimental-csschunking-strict-is-only-suppo","errorCode":null,"errorMessage":"`experimental.cssChunking: \"strict\"` is only supported with webpack. Please remove the option or run Next.js with webpack in ${configFileName}.","messagePattern":"`experimental\\.cssChunking: \"strict\"` is only supported with webpack\\. Please remove the option or run Next\\.js with webpack in (.+?)\\.","errorType":"exception","errorClass":"Error","httpStatus":null,"severity":"error","filePath":"packages/next/src/server/config.ts","lineNumber":597,"sourceCode":"    phase !== PHASE_TEST\n  ) {\n    if (result.experimental.durableUseCacheEntries && !process.env.TURBOPACK) {\n      throw new Error(\n        `\\`experimental.durableUseCacheEntries: true\\` is only supported with Turbopack. ` +\n          `Please remove the option or run Next.js with Turbopack in ${configFileName}.`\n      )\n    }\n\n    const cssChunkingValue = result.experimental.cssChunking\n    const cssChunkingMode = resolveCssChunkingMode(cssChunkingValue)\n    if (cssChunkingMode === 'graph' && !process.env.TURBOPACK) {\n      throw new Error(\n        `\\`experimental.cssChunking: \"graph\"\\` is only supported with Turbopack. ` +\n          `Please remove the option or run Next.js with Turbopack in ${configFileName}.`\n      )\n    }\n    if (cssChunkingMode === 'strict' && process.env.TURBOPACK) {\n      throw new Error(\n        `\\`experimental.cssChunking: \"strict\"\\` is only supported with webpack. ` +\n          `Please remove the option or run Next.js with webpack in ${configFileName}.`\n      )\n    }\n    // Only error when `false` was set explicitly. `undefined` (the default) also resolves to\n    // `'off'` but that's the implicit default and must not error on Turbopack.\n    if (cssChunkingValue === false && process.env.TURBOPACK) {\n      throw new Error(\n        `\\`experimental.cssChunking: false\\` is only supported with webpack. ` +\n          `Please remove the option or run Next.js with webpack in ${configFileName}.`\n      )\n    }\n\n    if (\n      result.experimental.turbopackRustReactCompiler &&\n      !process.env.TURBOPACK\n    ) {\n      throw new Error(","sourceCodeStart":579,"sourceCodeEnd":615,"githubUrl":"https://github.com/vercel/next.js/blob/34433fd12ee8074ea3f47af9f36255c7390d0301/packages/next/src/server/config.ts#L579-L615","documentation":"Config validation in assignDefaultsAndValidate: experimental.cssChunking resolved to the 'strict' mode, but that mode is only implemented for webpack while the current run uses Turbopack. The guard fires outside production-server phases (build/dev) and tells the user to drop the option or run with webpack in their config file.","triggerScenarios":"experimental.cssChunking 'strict' mode is used without webpack.","commonSituations":"cssChunking: 'strict' in next.config while running with Turbopack.","solutions":["Remove experimental.cssChunking: \"strict\", or run Next.js with webpack."],"exampleFix":null,"handlingStrategy":"validation","validationCode":null,"typeGuard":null,"tryCatchPattern":null,"preventionTips":[],"tags":[],"backgroundTag":null,"analyzedSha":"34433fd12ee8074ea3f47af9f36255c7390d0301","analyzedAt":"2026-08-19T02:10:13.922Z","contentChangedAt":"2026-08-19T02:10:13.922Z","schemaVersion":2},"datasetVersion":"2026-09-23T08:17:48.524Z"}