What version of Hugo are you using (hugo version)?

$ hugo version 0.76.5

Does this issue reproduce with the latest release?

Yes and also with version 0.76.4.

It doesn't happen with version 0.74.0

Problem

We are getting a long list of warning for like this for all our languages ("de","fr","es","it","nl","fr-be","nl-be", "pl", "bg", "ro", "hu", "cz","com","at"), that causes our build pipelines buffer to exceed it's limits:

16:12:12 WARN 2020/10/15 14:12:12 Failed to get translated string for language "art-x-cz" and ID "ratings": %!s()
16:12:12 WARN 2020/10/15 14:12:12 Failed to get translated string for language "art-x-cz" and ID "showmore": %!s()
16:12:12 WARN 2020/10/15 14:12:12 Failed to get translated string for language "art-x-cz" and ID "techdata": %!s()
16:12:12 WARN 2020/10/15 14:12:12 Failed to get translated string for language "art-x-cz" and ID "defaultHeadline": %!s()
16:12:12 WARN 2020/10/15 14:12:12 Failed to get translated string for language "art-x-cz" and ID "showmore": %!s()
16:12:12 WARN 2020/10/15 14:12:12 Failed to get translated string for language "art-x-cz" and ID "homepage": %!s()
16:12:12 WARN 2020/10/15 14:12:12 Failed to get translated string for language "art-x-cz" and ID "Modelle": %!s()
16:12:12 WARN 2020/10/15 14:12:12 Failed to get translated string for language "art-x-cz" and ID "techdata": %!s()
16:12:12 WARN 2020/10/15 14:12:12 Failed to get translated string for language "art-x-cz" and ID "showmore": %!s()
16:12:12 WARN 2020/10/15 14:12:12 Failed to get translated string for language "art-x-cz" and ID "introtext": %!s()
16:12:12 WARN 2020
16:12:12
16:12:12 Build failed: RangeError [ERR_CHILD_PROCESS_STDIO_MAXBUFFER]: stdout maxBuffer length exceeded

There is no trace of any language "art-x-cz or similiar in our codebase.

Could you please look into this?

Thanks a lot for your support