diff --git a/src/bun_core/fmt.rs b/src/bun_core/fmt.rs
index 4e3338afb90f..c9e92878c346 100644
--- a/src/bun_core/fmt.rs
+++ b/src/bun_core/fmt.rs
@@ -327,7 +327,7 @@ impl Display for DependencyUrlFormatter<'_> {
         let mut remain = self.url;
         while let Some(slash) = crate::strings::index_of_char_usize(remain, b'/') {
             write_bytes(f, &remain[..slash])?;
-            f.write_str("%2f")?;
+            f.write_str("%2F")?;
             remain = &remain[slash + 1..];
         }
         write_bytes(f, remain)
diff --git a/src/install/NetworkTask.rs b/src/install/NetworkTask.rs
index e89078efa2c4..5ec584800a65 100644
--- a/src/install/NetworkTask.rs
+++ b/src/install/NetworkTask.rs
@@ -425,7 +425,7 @@ impl NetworkTask {
             // "npm" CLI requests the manifest with the encoded name.
             let encoded_name_storage;
             let encoded_name: &[u8] = if strings::index_of_char(name, b'/').is_some() {
-                encoded_name_storage = name.replace(b"/", b"%2f");
+                encoded_name_storage = name.replace(b"/", b"%2F");
                 &encoded_name_storage
             } else {
                 name
diff --git a/test/cli/install/bun-add.test.ts b/test/cli/install/bun-add.test.ts
index 2a0f346eb12b..102419e5d56c 100644
--- a/test/cli/install/bun-add.test.ts
+++ b/test/cli/install/bun-add.test.ts
@@ -466,10 +466,10 @@ it("should handle @scoped names", async () => {
     env,
   });
   const err = await stderr.text();
-  expect(err.split(/\r?\n/)).toContain(`error: GET http://localhost:${port}/@bar%2fbaz - 404`);
+  expect(err.split(/\r?\n/)).toContain(`error: GET http://localhost:${port}/@bar%2Fbaz - 404`);
   expect(await stdout.text()).toEqual(expect.stringContaining("bun add v1."));
   expect(await exited).toBe(1);
-  expect(urls.sort()).toEqual([`${root_url}/@bar%2fbaz`]);
+  expect(urls.sort()).toEqual([`${root_url}/@bar%2Fbaz`]);
   expect(requested).toBe(1);
   try {
     await access(join(package_dir, "bun.lockb"));
diff --git a/test/cli/install/bun-create.test.ts b/test/cli/install/bun-create.test.ts
index d939581968f5..55e51ee32e34 100644
--- a/test/cli/install/bun-create.test.ts
+++ b/test/cli/install/bun-create.test.ts
@@ -48,7 +48,7 @@ it("should create selected template with @ prefix", async () => {
 
   const err = await stderr.text();
   expect(err.split(/\r?\n/)).toContain(
-    `error: GET https://registry.npmjs.org/@quick-start%2fcreate-some-template - 404`,
+    `error: GET https://registry.npmjs.org/@quick-start%2Fcreate-some-template - 404`,
   );
 });
 
@@ -63,7 +63,7 @@ it("should create selected template with @ prefix implicit `/create`", async ()
   });
 
   const err = await stderr.text();
-  expect(err.split(/\r?\n/)).toContain(`error: GET https://registry.npmjs.org/@second-quick-start%2fcreate - 404`);
+  expect(err.split(/\r?\n/)).toContain(`error: GET https://registry.npmjs.org/@second-quick-start%2Fcreate - 404`);
   await exited;
 });
 
@@ -78,7 +78,7 @@ it("should create selected template with @ prefix implicit `/create` with versio
   });
 
   const err = await stderr.text();
-  expect(err.split(/\r?\n/)).toContain(`error: GET https://registry.npmjs.org/@second-quick-start%2fcreate - 404`);
+  expect(err.split(/\r?\n/)).toContain(`error: GET https://registry.npmjs.org/@second-quick-start%2Fcreate - 404`);
 
   await exited;
 });
diff --git a/test/cli/install/bun-info.test.ts b/test/cli/install/bun-info.test.ts
index 116d07fe3b15..c5a1e321414b 100644
--- a/test/cli/install/bun-info.test.ts
+++ b/test/cli/install/bun-info.test.ts
@@ -277,6 +277,40 @@ describe.concurrent("bun info", () => {
       expect(output).toContain("TypeScript definitions");
     });
 
+    // https://github.com/oven-sh/bun/issues/30311
+    // GitLab's npm registry rejects lowercase %2f; match npm CLI (uppercase %2F).
+    it("should use uppercase %2F in the manifest URL for scoped names", async () => {
+      const requestPaths: string[] = [];
+      using server = Bun.serve({
+        port: 0,
+        fetch(req) {
+          const url = new URL(req.url);
+          requestPaths.push(url.pathname);
+          const path = url.pathname.replaceAll("%2f", "/").replaceAll("%2F", "/");
+          if (path === "/@scoped/has-bin-entry") {
+            return Response.json({
+              name: "@scoped/has-bin-entry",
+              "dist-tags": { latest: "1.0.0" },
+              versions: { "1.0.0": { name: "@scoped/has-bin-entry", version: "1.0.0" } },
+            });
+          }
+          return new Response("not found", { status: 404 });
+        },
+      });
+
+      const testDir = tempDirWithFiles("pm-view-scoped", {
+        "package.json": JSON.stringify({ name: "x", version: "0.0.1" }),
+        ".npmrc": `@scoped:registry=http://localhost:${server.port}/\n`,
+      });
+
+      const { output, error, code } = await runCommand([bunExe(), "pm", "view", "@scoped/has-bin-entry"], testDir);
+
+      expect(requestPaths).toEqual(["/@scoped%2Fhas-bin-entry"]);
+      expect(error).not.toContain("error:");
+      expect(output).toContain("@scoped/has-bin-entry@1.0.0");
+      expect(code).toBe(0);
+    });
+
     it("should handle .", async () => {
       const testDir = await setupTest();
       const { output, error, code } = await runCommand([bunExe(), "pm", "view", "."], testDir, false);
diff --git a/test/cli/install/bun-install-registry.test.ts b/test/cli/install/bun-install-registry.test.ts
index 5bf0cca96d9e..df2d3f445d86 100644
--- a/test/cli/install/bun-install-registry.test.ts
+++ b/test/cli/install/bun-install-registry.test.ts
@@ -4935,6 +4935,69 @@ test("name from manifest is scoped and url encoded", async () => {
   ]);
 });
 
+// https://github.com/oven-sh/bun/issues/30311
+// GitLab's npm registry rejects lowercase %2f; match npm CLI (uppercase %2F).
+test("scoped package manifest url uses uppercase %2F", async () => {
+  const requestPaths: string[] = [];
+  using server = Bun.serve({
+    port: 0,
+    fetch(req) {
+      const url = new URL(req.url);
+      requestPaths.push(url.pathname);
+      const path = url.pathname.replaceAll("%2f", "/").replaceAll("%2F", "/");
+      if (path === "/@scoped/has-bin-entry") {
+        return Response.json({
+          name: "@scoped/has-bin-entry",
+          "dist-tags": { latest: "1.0.0" },
+          versions: {
+            "1.0.0": {
+              name: "@scoped/has-bin-entry",
+              version: "1.0.0",
+              dist: {
+                shasum: "611b2b566718e05e8643fe872923ed91342b039a",
+                tarball: `http://localhost:${server.port}/@scoped/has-bin-entry/-/has-bin-entry-1.0.0.tgz`,
+              },
+            },
+          },
+        });
+      }
+      if (path.endsWith("/has-bin-entry-1.0.0.tgz")) {
+        return new Response(
+          Bun.file(
+            join(import.meta.dir, "registry", "packages", "@scoped", "has-bin-entry", "has-bin-entry-1.0.0.tgz"),
+          ),
+        );
+      }
+      return new Response("not found", { status: 404 });
+    },
+  });
+
+  await Promise.all([
+    write(
+      packageJson,
+      JSON.stringify({
+        name: "foo",
+        dependencies: { "@scoped/has-bin-entry": "1.0.0" },
+      }),
+    ),
+    write(join(packageDir, ".npmrc"), `@scoped:registry=http://localhost:${server.port}/\n`),
+  ]);
+
+  const { stdout, stderr, exited } = spawn({
+    cmd: [bunExe(), "install"],
+    cwd: packageDir,
+    stdout: "pipe",
+    stderr: "pipe",
+    env,
+  });
+  const [out, err, code] = await Promise.all([stdout.text(), stderr.text(), exited]);
+
+  expect(requestPaths).toEqual(["/@scoped%2Fhas-bin-entry", "/@scoped/has-bin-entry/-/has-bin-entry-1.0.0.tgz"]);
+  expect(err).not.toContain("error:");
+  expect(out).toContain("+ @scoped/has-bin-entry@1.0.0");
+  expect(code).toBe(0);
+});
+
 describe("update", () => {
   test("duplicate peer dependency (one package is invalid_package_id)", async () => {
     await write(
diff --git a/test/cli/install/bun-install-security-provider.test.ts b/test/cli/install/bun-install-security-provider.test.ts
index 81e00a3c420b..20a3f28d4f08 100644
--- a/test/cli/install/bun-install-security-provider.test.ts
+++ b/test/cli/install/bun-install-security-provider.test.ts
@@ -750,7 +750,7 @@ describe("Large payload via ipc pipe", () => {
     customRegistry: (urls, ctx) => {
       return async (request: Request) => {
         urls.push(request.url);
-        const url = request.url.replaceAll("%2f", "/");
+        const url = request.url.replaceAll("%2f", "/").replaceAll("%2F", "/");
         expect(request.method).toBe("GET");
         if (url.endsWith(".tgz")) {
           return new Response(barTarballBytes);
diff --git a/test/cli/install/bun-install-tarball-integrity.test.ts b/test/cli/install/bun-install-tarball-integrity.test.ts
index 98bc78c8e5a3..fdb05038123b 100644
--- a/test/cli/install/bun-install-tarball-integrity.test.ts
+++ b/test/cli/install/bun-install-tarball-integrity.test.ts
@@ -757,7 +757,7 @@ describe.concurrent.each(["hoisted", "isolated"] as const)("tarball download fai
       const urls: string[] = [];
       let tarballStatus = 200;
       setContextHandler(ctx, async request => {
-        const url = request.url.replaceAll("%2f", "/");
+        const url = request.url.replaceAll("%2f", "/").replaceAll("%2F", "/");
         urls.push(url);
         if (url.endsWith(".tgz")) {
           if (tarballStatus !== 200) {
diff --git a/test/cli/install/bun-install.test.ts b/test/cli/install/bun-install.test.ts
index 51f91d596712..ed07a3bce91f 100644
--- a/test/cli/install/bun-install.test.ts
+++ b/test/cli/install/bun-install.test.ts
@@ -645,7 +645,7 @@ describe.concurrent("bun-install", () => {
   it("should handle @scoped authentication", async () => {
     await withContext(defaultOpts, async ctx => {
       let seen_token = false;
-      const url = `${ctx.registry_url}@foo%2fbar`;
+      const url = `${ctx.registry_url}@foo%2Fbar`;
       const urls: string[] = [];
       setContextHandler(ctx, async request => {
         expect(request.method).toBe("GET");
@@ -3310,7 +3310,7 @@ describe.concurrent("bun-install", () => {
         "1 package installed",
       ]);
       expect(await exited).toBe(0);
-      expect(urls.sort()).toEqual([`${ctx.registry_url}@barn%2fmoo`, `${ctx.registry_url}@barn/moo-0.1.0.tgz`]);
+      expect(urls.sort()).toEqual([`${ctx.registry_url}@barn%2Fmoo`, `${ctx.registry_url}@barn/moo-0.1.0.tgz`]);
       expect(ctx.requested).toBe(2);
       expect(await readdirSorted(join(ctx.package_dir, "node_modules"))).toEqual([".cache", "@barn", "moo"]);
       expect(await readdirSorted(join(ctx.package_dir, "node_modules", "@barn"))).toEqual(["moo"]);
@@ -3445,7 +3445,7 @@ describe.concurrent("bun-install", () => {
       ]);
       expect(await exited1).toBe(0);
       expect(urls.sort()).toEqual([
-        `${ctx.registry_url}@barn%2fmoo`,
+        `${ctx.registry_url}@barn%2Fmoo`,
         `${ctx.registry_url}@barn/moo-0.1.0.tgz`,
         `${ctx.registry_url}bar`,
         `${ctx.registry_url}bar-0.0.2.tgz`,
diff --git a/test/cli/install/bun-update.test.ts b/test/cli/install/bun-update.test.ts
index 7859e7f56388..c100320baf9f 100644
--- a/test/cli/install/bun-update.test.ts
+++ b/test/cli/install/bun-update.test.ts
@@ -201,7 +201,7 @@ for (const { input } of [{ input: { baz: "~0.0.3", moo: "~0.1.0" } }]) {
     ]);
     expect(await exited1).toBe(0);
     expect(urls.sort()).toEqual([
-      `${root_url}/@barn%2fmoo`,
+      `${root_url}/@barn%2Fmoo`,
       `${root_url}/@barn/moo-0.1.0.tgz`,
       `${root_url}/baz`,
       `${root_url}/baz-0.0.3.tgz`,
@@ -264,7 +264,7 @@ for (const { input } of [{ input: { baz: "~0.0.3", moo: "~0.1.0" } }]) {
     }
     expect(await exited2).toBe(0);
     expect(urls.sort()).toEqual([
-      `${root_url}/@barn%2fmoo`,
+      `${root_url}/@barn%2Fmoo`,
       `${root_url}/@barn/moo-0.1.0.tgz`,
       `${root_url}/baz`,
       tilde ? `${root_url}/baz-0.0.5.tgz` : `${root_url}/baz-0.0.3.tgz`,
diff --git a/test/cli/install/bunx.test.ts b/test/cli/install/bunx.test.ts
index cb99066c38c7..c1a339c7259e 100644
--- a/test/cli/install/bunx.test.ts
+++ b/test/cli/install/bunx.test.ts
@@ -1149,7 +1149,7 @@ describe("package name aliases", () => {
     const paths = urls.map(u => new URL(u).pathname);
     // The manifest request must be for the real package, and must never hit
     // the squatter package name.
-    expect(paths).toContain("/@anthropic-ai%2fclaude-code");
+    expect(paths).toContain("/@anthropic-ai%2Fclaude-code");
     expect(paths).not.toContain("/claude");
     // Install fails because the mock registry 404s; that's fine, we only care
     // about which manifest was requested.
diff --git a/test/cli/install/dummy.registry.ts b/test/cli/install/dummy.registry.ts
index 63798c7e2027..7b6668a91358 100644
--- a/test/cli/install/dummy.registry.ts
+++ b/test/cli/install/dummy.registry.ts
@@ -82,7 +82,7 @@ function defaultHandler(): Response {
 
 /**
  * Extract the test ID prefix from a URL path.
- * URL format: /test-123/package-name or /test-123/@scope%2fpackage-name
+ * URL format: /test-123/package-name or /test-123/@scope%2Fpackage-name
  */
 function extractTestPrefix(url: string): { prefix: string; remainingPath: string } | null {
   const urlObj = new URL(url);
@@ -171,7 +171,7 @@ export function dummyRegistryForContext(
   let retryCountsByURL = new Map<string, number>();
   const _handler: Handler = async request => {
     urls.push(request.url);
-    const url = request.url.replaceAll("%2f", "/");
+    const url = request.url.replaceAll("%2f", "/").replaceAll("%2F", "/");
 
     let status = 200;
 
@@ -247,7 +247,7 @@ export function dummyRegistry(
   let retryCountsByURL = new Map<string, number>();
   const _handler: Handler = async request => {
     urls.push(request.url);
-    const url = request.url.replaceAll("%2f", "/");
+    const url = request.url.replaceAll("%2f", "/").replaceAll("%2F", "/");
 
     let status = 200;