ERROR POSTCSS: failed to transform "/css/eureka.css" (text/css): resource

[Steve-Shao]

Describe the bug

I've been using the eureka theme for a few years, but in a recent edit, when I used hugo server, I got:

ERROR POSTCSS: failed to transform "/css/eureka.css" (text/css): resource "css/eureka.css_59122205213644db2a335025f85b41bf" not found in file cache
Built in 184 ms
Error: error building site: POSTCSS: failed to transform "/css/eureka.css" (text/css): resource "css/eureka.css_59122205213644db2a335025f85b41bf" not found in file cache

I searched on the web and this error seems to happen when hugo upgrades, but I've not found a good solution that works for me.

[yashlala]

I don't know why this happens -- but I can tell you the steps that fixed the problem for me:

1. Go to the eureka submodules directory, and run hugo mod clean.
2. Run hugo mod clean in the project root.
3. Run hugo build to build the project.

Hopefully this helps.

[thebeanogamer]

I also ran into this, https://discourse.gohugo.io/t/error-building-site-postcss/31766/2 fixed it for me