Build failure: CSS modules + PostCSS in the RSC environment
#1.509 geöffnet am 22.05.2026
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Beschreibung
This issue was created by an agent analysing CI failures from the Next.js Deploy Suite (vinext
mainvs Next.jsv16.2.6, 2026-05-22).
Problem
When an app combines CSS modules with PostCSS configuration in the RSC environment, the build fails with Custom deploy script failed: undefined (1). Likely a CSS pipeline interaction between @vitejs/plugin-rsc and PostCSS that does not handle CSS module class hashing through PostCSS-processed files.
CSS modules + PostCSS in RSC environment fails to build
Estimated Impact
~1 test failures across the deploy suite.
Affected Test Suites
test/e2e/app-dir/css-modules-rsc-postcss/css-modules-rsc-postcss.test.ts
Recommendation
-
Reproduce first in vinext's own test suite. Add a fixture combining a
*.module.cssimport with a custompostcss.config.jsin the RSC environment. -
Run PostCSS before CSS-module class hashing. Make sure
@vitejs/plugin-rscruns PostCSS first, then the CSS-module class hashing pass.
Part of #1328.