convert-to-cpm

Convert to Central Package Management

Migrate .NET projects from per-project package versioning to NuGet Central Package Management (CPM). CPM centralizes all package versions into a single Directory.Packages.props file, making version governance and upgrades easier across multi-project repositories.

When to Use

• The user wants to adopt Central Package Management for a .NET repository, solution, or project
• Package versions are scattered across many .csproj, .fsproj, or .vbproj files and the user wants a single source of truth
• The user mentions Directory.Packages.props, CPM, or centralizing NuGet versions
• The user wants to update, bump, upgrade, align, or sync a NuGet package version across multiple projects -- CPM is the recommended approach for managing shared package versions, so suggest converting to CPM as part of the update if the projects use PackageReference and CPM is not already enabled
• Package versions are out of sync, conflicting, or mismatched across projects and the user wants to resolve or unify them

When Not to Use

• The repository already has CPM fully enabled for all in-scope projects
• The user is working with packages.config-based projects (must first migrate to PackageReference)
• The user wants to manage versions via a custom MSBuild property file without using CPM

Inputs

Workflow

Step 1: Determine scope

• Single project: User specifies a .csproj, .fsproj, or .vbproj.
• Solution: User specifies a .sln or .slnx. List projects with dotnet sln list.
• Repository/directory: No specific file given. Find all project files recursively from the first common ancestor directory of all .NET projects in scope.

If the scope is unclear, ask the user.

Guard: Check for packages.config projects. Before proceeding, check whether any project in scope uses packages.config instead of PackageReference. Look for packages.config files alongside project files. If any packages.config usage is detected, stop and do not proceed with the conversion. Inform the user that CPM requires projects with PackageReference format and that they must first migrate from packages.config to PackageReference (e.g., using Visual Studio's built-in migration or the dotnet migrate tooling). This skill cannot perform that migration.

Step 2: Establish baseline build

Before making any changes, verify the scope builds successfully and capture a baseline binlog and package list. Run dotnet clean, then dotnet build -bl:baseline.binlog, then dotnet package list --format json > baseline-packages.json. Read baseline-comparison.md for the full procedure and fallback options. If the baseline build fails, stop and inform the user -- the scope must build cleanly before conversion. Do not delete baseline.binlog or baseline-packages.json -- they are needed for the post-conversion comparison and report.

Step 3: Check for existing CPM

Search for any existing Directory.Packages.props in scope or ancestor directories. If CPM is already fully enabled, inform the user and stop. If a Directory.Packages.props exists without CPM enabled, ask whether to add the property to the existing file or create a new one.

Step 4: Audit package references

Run dotnet package list --format json to get the resolved package references across all in-scope projects. Also scan <Import> elements to discover shared .props/.targets files containing package references.

Check for complexities: version conflicts, MSBuild property-based versions, conditional references, security advisories, and existing VersionOverride usage. Read audit-complexities.md for the full checklist.

Present audit results to the user before proceeding, including:

• A table of each package, its version(s), and which projects use it
• Any version conflicts, security advisories, or complexities requiring decisions

When version conflicts exist, present each one individually with the affected projects, the distinct versions found, and the resolution options (align to highest, use VersionOverride, etc.) with their trade-offs. Do not upgrade any package beyond the highest version already in use across the scope -- this avoids introducing version incompatibilities or breaking changes that are unrelated to the CPM conversion itself. Note any known security advisories or other upgrade opportunities as follow-up items for the user to address after the conversion is complete. Ask the user to decide on each conflict before proceeding. Read audit-complexities.md - Same package with different versions for the resolution workflow and presentation format.

Step 5: Create or update Directory.Packages.props

Create the file with dotnet new packagesprops (.NET 8+) or manually. Add a <PackageVersion> entry for each unique package sorted alphabetically. For conditional versions or VersionOverride patterns, read directory-packages-props.md.

Step 6: Update project files

Remove the Version attribute from every <PackageReference> that now has a corresponding <PackageVersion>. Also update any shared .props/.targets files identified in step 4.

• Preserve all other attributes (PrivateAssets, IncludeAssets, ExcludeAssets, GeneratePathProperty, Aliases)
• Preserve conditional <ItemGroup> elements -- only remove the Version attribute within them
• Retain each file's existing indentation style (spaces vs. tabs, indentation depth) and blank lines -- do not reformat or reorganize unchanged lines
• Use VersionOverride (with user confirmation) when a project needs a different version than the central one

Step 7: Handle MSBuild version properties

For PackageReference items that used MSBuild properties for versions, determine whether to inline the resolved value or keep the property reference in Directory.Packages.props. After validation succeeds in step 8, remove inlined version properties from Directory.Build.props or other files, verifying they have no remaining references. Read msbuild-property-handling.md for the decision workflow, import order requirements, and cleanup procedure.

Step 8: Restore and validate

Run a clean restore and build, capturing a post-conversion binlog and package list. Run dotnet clean, then dotnet build -bl:after-cpm.binlog, then dotnet package list --format json > after-cpm-packages.json. Read baseline-comparison.md for the full procedure. If errors occur, read validation-and-errors.md for NuGet error codes and multi-TFM guidance.

Do not delete or clean up any artifacts (baseline.binlog, after-cpm.binlog, baseline-packages.json, after-cpm-packages.json). These files must be preserved for the user to inspect after the conversion. They are deliverables, not temporary files.

Step 9: Post-conversion report

You must create a convert-to-cpm.md file alongside the binlog and JSON artifacts. Do not skip this step or substitute inline chat output for the file -- the user needs a persistent, shareable document. This file should be self-contained and shareable -- suitable for a pull request description, a team review, or a record of what was done. Structure the report with the following sections:

Section 1: Conversion overview

Summarize what was converted: the scope (project, solution, or repository), number of projects converted, total packages centralized, any projects or packages that were skipped, and any MSBuild properties that were inlined or removed. This gives the reader immediate context.

Section 2: Version conflict resolutions

If any version conflicts were encountered, list each one with:

• The package name and all versions that were found across projects
• Which projects used each version
• What the user decided (aligned to highest, used VersionOverride, etc.)
• The practical impact: which projects now resolve a different version than before, and which are unchanged

If no conflicts were found, state that all packages had consistent versions across projects -- this is a positive signal worth noting.

Section 3: Package comparison -- baseline vs. result

Compare baseline-packages.json and after-cpm-packages.json per project. See baseline-comparison.md for the comparison procedure. Present two tables:

• Changes table: Packages where the resolved version changed, a VersionOverride was introduced, or a package was added/removed. Include a status column explaining what changed and why (e.g., "VersionOverride -- project retains pinned version", "Aligned to highest version").
• Unchanged table: All other packages, confirming they resolve identically to baseline.

If there are no changes at all, state that the conversion is fully version-neutral -- this is the ideal outcome and provides reassurance.

Section 4: Risk assessment

Provide a clear confidence statement:

• [Low risk] -- Conversion is version-neutral; all packages resolve to the same versions as baseline. The build and restore succeeded. Recommend running dotnet test as a final check.
• [Moderate risk] -- Some packages changed versions (e.g., minor/patch alignment). List the affected packages and projects. Recommend reviewing the changes table and running dotnet test to verify no regressions.
• [High risk] -- Major version changes were applied, or packages were added/removed unexpectedly. Recommend careful review, running dotnet test, and comparing binlogs before merging.

Call out any specific warnings: VersionOverride usage that partially undermines centralization, or MSBuild property removal that could affect other build logic.

Section 5: Follow-up items

List any items identified during the conversion that the user should address separately after the CPM conversion is complete. These are intentionally out of scope for the conversion itself but important for the user to act on. Common follow-up items include:

• Security advisories: If any package versions are known to have security vulnerabilities (detected via dotnet package list --vulnerable or noted during the audit), list each advisory with the package name, current version, affected projects, and the minimum patched version. These upgrades are out of scope for the CPM conversion to avoid introducing version incompatibilities or breaking changes.
• Deprecated packages: If any packages are deprecated, note the recommended replacement.
• Version alignment opportunities: If VersionOverride was used to preserve differing versions, note that the user may want to align these in the future once the affected projects can be validated against the central version.
• Test validation: Recommend running dotnet test to validate runtime behavior beyond build success, especially if any version conflicts were resolved by aligning to the highest version.

Present follow-up items as a numbered checklist so the user can track them.

Section 6: Artifacts and how to use them

List the artifacts produced during conversion and explain how to use them:

• baseline.binlog and after-cpm.binlog -- MSBuild binary logs captured before and after conversion. These are available for manual validation and troubleshooting if needed.
• baseline-packages.json and after-cpm-packages.json -- Machine-readable snapshots of resolved package versions per project, used to produce the comparison tables above.
• convert-to-cpm.md -- This report file, suitable for use as a pull request description or team review artifact.

Recommend the user run dotnet test to validate runtime behavior beyond build success. If any version conflicts were resolved by aligning to the highest version, recommend reviewing the release notes for the affected packages.

Validation

• Baseline build succeeded before any changes were made
• Directory.Packages.props exists with ManagePackageVersionsCentrally set to true
• Every in-scope PackageReference either has no Version attribute or uses VersionOverride
• Every referenced package has a corresponding PackageVersion entry
• dotnet restore and dotnet build complete without errors from a clean state
• Package list comparison shows no unexpected version changes
• No orphaned version properties remain (unless intentionally kept)

More Info

• Central Package Management documentation
• Validation and common errors