What Broke in the Build
Two files in the publish graph would land at the same relative output path, so the SDK fails instead of overwriting one silently.
Fix the underlying build failure
Use the error output to identify the colliding relative path or paths.
Rename one file, change its Link or TargetPath, or exclude one from publish.
Retry with dotnet publish -c Release.
Validation
Re-run the failing command and confirm the original code/message is gone, and confirm expected artifacts or outputs exist (packages restored, build/publish succeeds).
Why the Build Fails
Usually this comes down to a project and project reference both publish a same-named content file, two content or static web asset items share the same Link or RelativePath, or custom targets modify publish items and introduce collisions.
Prove the Build Path Is Clean
dotnet publish succeeds without NETSDK1152.
The publish directory contains the intended file set with no silent overwrites.
Typical Output
error NETSDK1152: Found multiple publish output files with the same relative path: appsettings.json.Mechanism
Publish computes a list of files with destination relative paths under the publish directory. If two files map to the same relative path, NETSDK1152 is emitted.
Keep Build Prerequisites Consistent
To prevent this, adopt naming conventions for content files across projects, and run publish in CI for representative apps to catch collisions early.
Docs and source code
NETSDK1152 message template
User-facing publish collision message template. - GitHub
<data name="DuplicatePublishOutputFiles" xml:space="preserve">
<value>NETSDK1152: Found multiple publish output files with the same relative path: {0}.</value>
<comment>{StrBegins="NETSDK1152: "}</comment>
</data>