Troubleshooting

The page is blank, or the script 404s

• Is the page asking for .js? The .ts is never served in a published site. Point your <script> at /js/app.js.
• Did the build run? Look for obj/<configuration>/<tfm>/pare/js/app.js.
• Did you call app.MapStaticAssets()? The build registers Pare's output as a static web asset, and MapStaticAssets serves it. With CreateSlimBuilder, also call builder.WebHost.UseStaticWebAssets(); without it an unpublished run answers requests that send Accept-Encoding with the build's compressed copies it cannot find, 200 and an empty body.
• Is / a 404 while /js/app.js works? Add app.UseDefaultFiles(); and app.UseRouting(); before app.MapStaticAssets();.

warning PARE200: not served

A foo.js sits next to foo.ts in wwwroot. Delete it (and any .gitignore rule for it). The build serves the stripped foo.ts from obj/.

warning PARE202: not served

A source outside wwwroot has no PareServeAt. Add one, or add PARE202 to NoWarn. See TypeScript outside wwwroot.

An edit does not show up under dotnet watch

• Did you call builder.AddPareDevelopment()? Without it a .ts save runs no build.
• Run dotnet watch from the project directory, not with --project from elsewhere.
• A PublishAot project needs <StartupHookSupport Condition="'$(Configuration)' == 'Debug'">true</StartupHookSupport>.
• A .ts file you added during the session is 404 until the next build. Press Ctrl+R.

More in Hot reload.

The build says error PARE100 to PARE107

Your TypeScript uses syntax that needs generated code. Error codes shows the plain JavaScript to write for each. Turn on "erasableSyntaxOnly": true in tsconfig.json so the editor warns you first.

error PARE001: syntax error

The file is not valid TypeScript at that position. Pare stops at the first syntax error. .tsx and JSX are not supported.

A type error went through

Pare does not check types. See Type checking in CI.

An import fails at run time but the file stripped fine

You imported a type without type: import { Foo } from "./foo.ts" where Foo is an interface. Pare cannot know, so it keeps the import. Write import type { Foo } or import { type Foo }, and set "verbatimModuleSyntax": true so tsc reminds you.

Visual Studio

Visual Studio 2026 (MSBuild 18) runs the task in MSBuild's .NET task host, a separate process. Visual Studio 2022 cannot build net10.0 projects at all.

linux-musl-arm64 and NativeAOT

.NET misreads the main thread's stack size there, so the deep-nesting check fails at once. Call TypeStripper.Strip (or pare_strip) from a thread you created.