Gracefully handle and surface projects that fail to load, instead of failing the whole solution silently

[JakeRadMSFT]

Summary

When a solution contains a project that cannot be evaluated or built in the current environment (e.g. a project targeting an OS-specific framework that isn't buildable on the host OS), the whole solution's design-time build is reported as failed and there is no clear, first-class surface telling the user which project failed and why. The rest of the solution is effectively degraded with no actionable signal.

Impact

• One un-loadable project silently degrades the experience for the entire solution.
• Users have no easy way to see which project failed or how to remediate it.
• Common cross-platform case: a project targeting a Windows-only framework opened on macOS/Linux fails to resolve targeting packs, but the remediation (e.g. enabling cross-OS targeting) is not surfaced.

Requested behavior

1. Load-what-you-can: projects that evaluate/build successfully should continue to provide full IntelliSense and be cached, independent of projects that fail.
2. Visible partial load: projects that fail to load should be shown explicitly (e.g. a badge in the solution view and entries in the Problems surface) with the reason for the failure — never silently dropped.
3. Actionable diagnostics: where the failure is a known/recoverable class (such as OS/framework-targeting incompatibility), include the specific remediation hint.
4. Dependency awareness: if a loadable project depends on a failed one, indicate the degraded state rather than reporting a generic solution-wide failure.

Notes

• Precedent: the full desktop IDE loads what it can and surfaces unloaded projects with a reason plus a reload affordance, rather than failing the whole solution.
• Silent auto-exclusion is explicitly not desired — exclusion/degradation must be visible and explained.

[pixzz170]

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