Error List and Build System Alert Synchronization in Visual Studio

Short answer: No — Visual Studio does not automatically remove IntelliSense-only warnings when a subsequent build succeeds. The Error List is fed by two independent pipelines (the compiler/linker and the background IntelliSense analyzer), and a clean build only clears entries that came from the build pipeline. IntelliSense entries persist until the file is re-analyzed, edited, saved, or the list is manually cleared. The behavior below reflects Visual Studio 2019/2022 for C# and C++ projects; other languages may route diagnostics differently, so verify against your version.

Why the entries persist

The background analyzer updates the Error List in response to document changes and re-analysis passes, not in response to build completion. A successful build tells the IDE "the compiler found nothing," but it does not instruct the IntelliSense engine to re-evaluate its earlier findings. You can confirm this directly: open the Error List (View → Error List), note that IntelliSense rows show "IntelliSense" in the Source column, then run a successful build and observe that those rows remain.

Showing only build-reported warnings

You do not need to suppress anything manually — the Error List toolbar already provides the control you want:

• Filter to the last build: In the Error List toolbar's filter drop-down, choose the option to show only diagnostics from the last build. This hides all IntelliSense rows and leaves only compiler/linker output from the most recent build. Caveat: it also hides build warnings from earlier builds that did not reappear in the current one.
• Uncheck the IntelliSense source: The same drop-down lets you toggle sources. Unchecking "IntelliSense" removes all IntelliSense entries from the visible list regardless of build status, while keeping build diagnostics visible.

Suppressing IntelliSense diagnostics globally

If you never want IntelliSense entries at all, go to Tools → Options → Text Editor → C# → Advanced and enable the option to suppress IntelliSense errors. After rebuilding, no IntelliSense rows appear in the Error List. Be aware this is a blunt instrument: it also removes the real-time squiggle feedback many developers rely on while editing, and it applies beyond just the Error List view.

What actually determines persistence

Whether an alert survives a clean build depends on which engine produced it:

• Build-produced diagnostics are replaced wholesale on each build — a clean build clears them.
• IntelliSense-produced diagnostics are owned by the background analyzer and are only refreshed when that engine re-runs (edit, save, re-analysis) or when you clear/filter the list.

Verification steps

1. Introduce a condition that triggers an IntelliSense warning but compiles cleanly; confirm the row appears with Source = IntelliSense.
2. Build successfully and confirm the IntelliSense row remains.
3. Apply the "last build only" filter and confirm the IntelliSense rows disappear while compiler output stays.
4. Optionally enable the suppress-IntelliSense-errors option, rebuild, and confirm no IntelliSense rows appear.

If your Error List behaves differently — for example IntelliSense rows vanish after builds — the most useful diagnostic detail is your exact Visual Studio version and project language, since diagnostic routing has changed across releases.