diff --git a/src/install/migration.zig b/src/install/migration.zig
index 888cac4d2c..7659779984 100644
--- a/src/install/migration.zig
+++ b/src/install/migration.zig
@@ -30,7 +30,7 @@ pub fn detectAndLoadOtherLockfile(
                 .step = .migrating,
                 .value = err,
                 .lockfile_path = "package-lock.json",
-                .format = .binary,
+                .format = .text,
             } };
         };
 
@@ -54,7 +54,7 @@ pub fn detectAndLoadOtherLockfile(
                 .step = .migrating,
                 .value = err,
                 .lockfile_path = "yarn.lock",
-                .format = .binary,
+                .format = .text,
             } };
         };
 
@@ -126,7 +126,7 @@ pub fn detectAndLoadOtherLockfile(
                 .step = .migrating,
                 .value = err,
                 .lockfile_path = "pnpm-lock.yaml",
-                .format = .binary,
+                .format = .text,
             } };
         };
 
@@ -1089,7 +1089,7 @@ pub fn migrateNPMLockfile(
             .migrated = .npm,
             .loaded_from_binary_lockfile = false,
             .serializer_result = .{},
-            .format = .binary,
+            .format = .text,
         },
     };
 }
diff --git a/src/install/yarn.zig b/src/install/yarn.zig
index 6baaf5e9cb..fbf9e66737 100644
--- a/src/install/yarn.zig
+++ b/src/install/yarn.zig
@@ -1684,7 +1684,7 @@ pub fn migrateYarnLockfile(
         .migrated = .yarn,
         .loaded_from_binary_lockfile = false,
         .serializer_result = .{},
-        .format = .binary,
+        .format = .text,
     } };
 
     return result;
diff --git a/test/regression/issue/migration-lockfile-format.test.ts b/test/regression/issue/migration-lockfile-format.test.ts
new file mode 100644
index 0000000000..db4c1ac95d
--- /dev/null
+++ b/test/regression/issue/migration-lockfile-format.test.ts
@@ -0,0 +1,132 @@
+import { expect, test } from "bun:test";
+import { existsSync } from "fs";
+import { bunEnv, bunExe, tempDir } from "harness";
+import { join } from "path";
+
+test("failing to migrate pnpm-lock.yaml should create bun.lock not bun.lockb", async () => {
+  using dir = tempDir("pnpm-migration-format", {
+    "package.json": JSON.stringify({
+      name: "test",
+      version: "1.0.0",
+      dependencies: {
+        "is-even": "1.0.0",
+      },
+    }),
+    // Create an invalid pnpm-lock.yaml that will fail to migrate
+    "pnpm-lock.yaml": `lockfileVersion: '9.0'
+importers:
+  .:
+    dependencies:
+      is-even:
+        specifier: 1.0.0
+        version: 1.0.0
+packages:
+  /is-even@1.0.0:
+    resolution: {integrity: sha512-invalid-integrity}
+    engines: {node: '>=0.10.0'}
+`,
+  });
+
+  const result = await Bun.spawn({
+    cmd: [bunExe(), "install"],
+    cwd: String(dir),
+    env: bunEnv,
+    stderr: "pipe",
+    stdout: "pipe",
+  }).exited;
+
+  // After failed migration, bun.lock should exist (not bun.lockb)
+  const bunLockPath = join(String(dir), "bun.lock");
+  const bunLockbPath = join(String(dir), "bun.lockb");
+
+  expect(existsSync(bunLockPath)).toBe(true);
+  expect(existsSync(bunLockbPath)).toBe(false);
+});
+
+// Note: This test verifies the fix but may pass even if migration succeeds
+// The key fix is that error paths return .format = .text instead of .format = .binary
+test("after yarn.lock exists, bun install should create bun.lock not bun.lockb", async () => {
+  using dir = tempDir("yarn-migration-format", {
+    "package.json": JSON.stringify({
+      name: "test",
+      version: "1.0.0",
+      dependencies: {
+        "is-number": "7.0.0",
+      },
+    }),
+    // Create a valid yarn.lock to ensure migration happens
+    "yarn.lock": `# THIS IS AN AUTOGENERATED FILE. DO NOT EDIT THIS FILE DIRECTLY.
+# yarn lockfile v1
+
+is-number@7.0.0:
+  version "7.0.0"
+  resolved "https://registry.yarnpkg.com/is-number/-/is-number-7.0.0.tgz#7535345b896734d5f80c4d06c50955527a14f12b"
+  integrity sha512-41Cifkg6e8TylSpdtTpeLVMqvSBEVzTttHvERD741+pnZ8ANv0004MRL43QKPDlK9cGvNp6NZWZUBlbGXYxxng==
+`,
+  });
+
+  await Bun.spawn({
+    cmd: [bunExe(), "install"],
+    cwd: String(dir),
+    env: bunEnv,
+    stderr: "pipe",
+    stdout: "pipe",
+  }).exited;
+
+  // After migration, bun.lock should exist (not bun.lockb)
+  const bunLockPath = join(String(dir), "bun.lock");
+  const bunLockbPath = join(String(dir), "bun.lockb");
+
+  expect(existsSync(bunLockPath)).toBe(true);
+  expect(existsSync(bunLockbPath)).toBe(false);
+});
+
+test("successful migration from package-lock.json should create bun.lock not bun.lockb", async () => {
+  using dir = tempDir("npm-migration-format", {
+    "package.json": JSON.stringify({
+      name: "test",
+      version: "1.0.0",
+      dependencies: {
+        "is-number": "7.0.0",
+      },
+    }),
+    "package-lock.json": JSON.stringify({
+      name: "test",
+      version: "1.0.0",
+      lockfileVersion: 3,
+      requires: true,
+      packages: {
+        "": {
+          name: "test",
+          version: "1.0.0",
+          dependencies: {
+            "is-number": "7.0.0",
+          },
+        },
+        "node_modules/is-number": {
+          version: "7.0.0",
+          resolved: "https://registry.npmjs.org/is-number/-/is-number-7.0.0.tgz",
+          integrity: "sha512-41Cifkg6e8TylSpdtTpeLVMqvSBEVzTttHvERD741+pnZ8ANv0004MRL43QKPDlK9cGvNp6NZWZUBlbGXYxxng==",
+          engines: {
+            node: ">=0.12.0",
+          },
+        },
+      },
+    }),
+  });
+
+  const result = await Bun.spawn({
+    cmd: [bunExe(), "install"],
+    cwd: String(dir),
+    env: bunEnv,
+    stderr: "pipe",
+    stdout: "pipe",
+  }).exited;
+
+  // After successful migration, bun.lock should exist (not bun.lockb)
+  const bunLockPath = join(String(dir), "bun.lock");
+  const bunLockbPath = join(String(dir), "bun.lockb");
+
+  expect(existsSync(bunLockPath)).toBe(true);
+  expect(existsSync(bunLockbPath)).toBe(false);
+});