[Bug] 404 on 5xx error from GitHub

[Vampire]

Component

• github-workflows-kt (library with the DSL)
• bindings server (https://bindings.krzeminski.it)
• I don't know

Action

@file:DependsOn("actions:cache__restore___major:[v5,v6-alpha)")

Expected

Works

Actual

404 answer for maven-metadata.xml

2026-07-20 03:30:16,365 <[]> <{request-id=jcrn302lq5kcoz7}> <fegithub.workflows.jitbindingserver.MetadataRoutes> ➡️ Requesting metadata for actions/cache/restore with major version
2026-07-20 03:30:16,366 <[]> <{request-id=jcrn302lq5kcoz7}> < io.ktor.server.Application> 404 Not Found: GET - /actions/cache__restore___major/maven-metadata.xml in 1ms

Right after the 404 the prefetching starts properly though, so it seems the information was at least retrieved from GitHub.

[Vampire]

Same right now with cache__save___major

[Vampire]

Retrying "helps", now failing for checkout___major

[Vampire]

Ths 6th retry finally got it through

[krzema12]

I found a code path that causes this problem:

• github-workflows-kt/shared-internal/src/main/kotlin/io/github/typesafegithub/workflows/shared/internal/GithubApi.kt

  Line 31 in ad1caac

  suspend fun fetchAvailableVersions(

  produces Either.Left (error)
• in

  github-workflows-kt/maven-binding-builder/src/main/kotlin/io/github/typesafegithub/workflows/mavenbinding/MavenMetadataBuilding.kt

  Line 15 in ad1caac

  internal suspend fun BindingsServerRequest.buildMavenMetadataFile(

  , availableVersions becomes an empty list:

  github-workflows-kt/maven-binding-builder/src/main/kotlin/io/github/typesafegithub/workflows/mavenbinding/MavenMetadataBuilding.kt

  Line 30 in ad1caac

  emptyList()

• the empty list causes the function to return null instead of the XML:

  github-workflows-kt/maven-binding-builder/src/main/kotlin/io/github/typesafegithub/workflows/mavenbinding/MavenMetadataBuilding.kt

  Line 46 in ad1caac

  val newest = availableVersions.maxOrNull() ?: return null

  , which is later translated to a HTTP 404

[Vampire]

But I'd say that is not the codepath in question.

1. in buildMavenMetadataFile we do prefetchBindingArtifacts on the availableVersions and the prefetch worked according to the log file sot the list was not empty
2. also it would have logged the error before assigning the empty list which also did not happen

Anyway it might be debatable whether an empty list of versions should cause a 404 or an XML with no versions in it.
If really no versions were found on GitHub without an error having happened, I think 404 would be correct, because no versions, no maven-metadata.xml file and that is correct.
But if there indeed was an error, it might not be appropriate to return 404, I'm not sure.

But either way, I don't think that is the code path here anyway.

[Vampire]

Also a retry went through, so I'd guess that on the retry the file was coming from cache, so building it was successful and it was added to the cache I guess, but I didn't check in the logs.

[krzema12]

Thanks for the insights. Either way, the next step is preparing a reproducer in a form of a characterization test. I just came back from vacation, and I'm planning to take a closer look soon-ish