Fix opaque NullReferenceException when a NuGet V3 package version is missing (FD-440)#1994
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Fix opaque NullReferenceException when a NuGet V3 package version is missing (FD-440)#1994droyad wants to merge 1 commit into
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…-440) When a requested package version doesn't exist on a NuGet V3 feed, the download failed with an opaque NullReferenceException thrown inside the (forked) NuGet.Commands SourceRepositoryDependencyProvider, which dereferences a null downloader returned for the absent version. Instead of going through that provider, NuGetV3LibDownloader now resolves the downloader from FindPackageByIdResource directly and null-checks it, throwing an actionable "version not found" error. This removes the buggy provider wrapper from the download path entirely; its throttle and ignore-failed-sources behaviour is irrelevant here, as Calamari passes no throttle and downloads from a single source. Co-Authored-By: Claude Opus 4.8 (1M context) <[email protected]>
droyad
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Jun 5, 2026
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| var findPackageByIdResource = sourceRepository.GetResourceAsync<FindPackageByIdResource>(CancellationToken.None) | ||
| .GetAwaiter() | ||
| .GetResult(); | ||
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| var packageIdentity = new PackageIdentity(packageId, version.ToNuGetVersion()); | ||
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| string targetTempNupkg = Path.Combine(targetPath, Path.GetRandomFileName()); | ||
| var packageDownloader = providers.GetPackageDownloaderAsync(new PackageIdentity(packageId, version.ToNuGetVersion()), sourceCacheContext, logger, CancellationToken.None) | ||
| .GetAwaiter() | ||
| .GetResult(); | ||
| var packageDownloader = findPackageByIdResource.GetPackageDownloaderAsync(packageIdentity, sourceCacheContext, logger, CancellationToken.None) | ||
| .GetAwaiter() | ||
| .GetResult(); |
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The change is essentially pulling the core of the method shown in this PR inline and adding the null check here - this assumes the linked PR doesn't get merged.
droyad
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Jun 9, 2026
| var packageDownloader = providers.GetPackageDownloaderAsync(new PackageIdentity(packageId, version.ToNuGetVersion()), sourceCacheContext, logger, CancellationToken.None) | ||
| .GetAwaiter() | ||
| .GetResult(); | ||
| var packageDownloader = findPackageByIdResource.GetPackageDownloaderAsync(packageIdentity, sourceCacheContext, logger, CancellationToken.None) |
Contributor
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I noticed sourceRepository.GetResourceAsync can return null, so we might need null handling for findPackageByIdResource as well
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Background
Deploying with a package set to download on the target, from a NuGet V3 feed, for a version that doesn't exist on the feed, failed with an opaque
NullReferenceException— no hint that the real problem is a missing/unpublished version:Customer-facing context and the end-to-end product repro are in FD-440.
The problem is described in this PR for NuGet.Client. But since we don't want to add more things ot it, and the likelyhood of this getting fixed upstream in a timely manner are low, this PR avoids the problem.
Verification
Reproduced and fixed end-to-end on a local Octopus Server: a
Run a Scriptstep running on a worker pool, referencingNewtonsoft.Jsonversion9999.9.9(which doesn't exist) from a NuGet V3 feed (https://api.nuget.org/v3/index.json), with the package acquired on the worker.Before (stock Calamari) — bare NRE wrapped by the retry message:
After (this change) — clear, actionable message, no
NullReferenceExceptionanywhere in the log:Automated coverage: integration test
GivesActionableErrorWhenV3FeedIsMissingTheRequestedVersiondownloads a missing version fromapi.nuget.org— fails with the exact NRE above without this change, passes with it.On the retries: the download still retries all attempts before the deployment fails — left as-is intentionally. A version that's absent right now may legitimately be published to the feed mid-window (e.g. a lagging CI push), so retrying is the desired behaviour. This change only improves the message; it doesn't alter the retry policy.
Fixes FD-440