diff --git a/npm/private/test/parse_pnpm_lock_tests.bzl b/npm/private/test/parse_pnpm_lock_tests.bzl
index 4f1ee5822f..72ac2d2424 100644
--- a/npm/private/test/parse_pnpm_lock_tests.bzl
+++ b/npm/private/test/parse_pnpm_lock_tests.bzl
@@ -185,7 +185,6 @@ packages:
                     "@aspect-test/d": "2.0.0_at_aspect-test_c_1.0.0",
                 },
                 "dev": False,
-                "optionalDependencies": {},
             },
         },
         {},
diff --git a/npm/private/test/utils_tests.bzl b/npm/private/test/utils_tests.bzl
index d3ccbbd1ab..50e9315b52 100644
--- a/npm/private/test/utils_tests.bzl
+++ b/npm/private/test/utils_tests.bzl
@@ -63,6 +63,8 @@ def test_version_supported(ctx):
     env = unittest.begin(ctx)
     utils.assert_lockfile_version(5.3)
     utils.assert_lockfile_version(5.4)
+    utils.assert_lockfile_version(6.0)
+    utils.assert_lockfile_version(6.1)
     msg = utils.assert_lockfile_version(1.2, testonly = True)
     asserts.equals(env, "npm_translate_lock requires lock_version at least 5.3, but found 1.2. Please upgrade to pnpm v6 or greater.", msg)
     msg = utils.assert_lockfile_version(99.99, testonly = True)
diff --git a/npm/private/transitive_closure.bzl b/npm/private/transitive_closure.bzl
index 0ef3f3931f..14b967fd45 100644
--- a/npm/private/transitive_closure.bzl
+++ b/npm/private/transitive_closure.bzl
@@ -59,9 +59,12 @@ def gather_transitive_closure(packages, package, no_optional, cache = {}):
                     for transitive_version in cache[package_key][transitive_name]:
                         if transitive_version not in transitive_closure[transitive_name]:
                             transitive_closure[transitive_name].append(transitive_version)
-            else:
+            elif package_key in packages:
                 # Recurse into the next level of dependencies
                 stack.append(_get_package_info_deps(packages[package_key], no_optional))
+            else:
+                msg = "Unknown package key: {} in {}".format(package_key, packages.keys())
+                fail(msg)
 
     result = dict()
     for key in sorted(transitive_closure.keys()):
diff --git a/npm/private/utils.bzl b/npm/private/utils.bzl
index b19d05bde3..02914c8e9a 100644
--- a/npm/private/utils.bzl
+++ b/npm/private/utils.bzl
@@ -76,7 +76,7 @@ def _parse_pnpm_package_key(pnpm_name, pnpm_version):
 def _convert_pnpm_v6_version_peer_dep(version):
     # Covert a pnpm lock file v6 version string of the format
     # version(@scope/peer@version)(@scope/peer@version)
-    # to a version_peer_version that is compatible with rules_js.
+    # to a pnpm lock file v5 version_peer_version that is compatible with rules_js.
     if version[-1] == ")":
         # There is a peer dep if the string ends with ")"
         peer_dep_index = version.find("(")
@@ -91,9 +91,9 @@ def _convert_pnpm_v6_version_peer_dep(version):
     return version
 
 def _convert_pnpm_v6_package_name(package_name):
-    # Covert a pnpm lock file v6 name/version string of the format
+    # Covert a pnpm lock file v6 /name/version string of the format
     # @scope/name@version(@scope/name@version)(@scope/name@version)
-    # to a @scope/name/version_peer_version that is compatible with rules_js.
+    # to a pnpm lock file v5 @scope/name/version_peer_version format that is compatible with rules_js.
     if package_name.startswith("/"):
         package_name = _convert_pnpm_v6_version_peer_dep(package_name)
         segments = package_name.rsplit("@", 1)
@@ -105,7 +105,29 @@ def _convert_pnpm_v6_package_name(package_name):
         return _convert_pnpm_v6_version_peer_dep(package_name)
 
 def _convert_v6_importers(importers):
-    # Convert pnpm lockfile v6 importers to a rules_js compatible format.
+    # Convert pnpm lockfile v6 importers to a rules_js compatible ~v5 format.
+    #
+    # v5 importers:
+    #   specifiers:
+    #      pkg-a: 1.2.3
+    #      pkg-b: ^4.5.6
+    #   deps:
+    #      pkg-a: 1.2.3
+    #   devDeps:
+    #      pkg-b: 4.10.1
+    #   ...
+    #
+    # v6 pushed the 'specifiers' and 'version' into subproperties:
+    #
+    #   deps:
+    #      pkg-a:
+    #         specifier: 1.2.3
+    #         version: 1.2.3
+    #   devDeps:
+    #      pkg-b:
+    #          specifier: ^4.5.6
+    #          version: 4.10.1
+
     result = {}
     for import_path, importer in importers.items():
         result[import_path] = {}
@@ -118,20 +140,25 @@ def _convert_v6_importers(importers):
     return result
 
 def _convert_v6_packages(packages):
-    # Convert pnpm lockfile v6 importers to a rules_js compatible format.
+    # Convert pnpm lockfile v6 importers to a rules_js compatible ~v5 format.
+    #
+    # v6 package metadata mainly changed formatting of metadata such as:
+    #
+    # dependency versions with peers:
+    #   v5: 2.0.0_@aspect-test+c@2.0.2
+    #   v6: 2.0.0(@aspect-test/c@2.0.2)
+
     result = {}
     for package, package_info in packages.items():
-        # dependencies
-        dependencies = {}
-        for dep_name, dep_version in package_info.get("dependencies", {}).items():
-            dependencies[dep_name] = _convert_pnpm_v6_package_name(dep_version)
-        package_info["dependencies"] = dependencies
-
-        # optionalDependencies
-        optional_dependencies = {}
-        for dep_name, dep_version in package_info.get("optionalDependencies", {}).items():
-            optional_dependencies[dep_name] = _convert_pnpm_v6_package_name(dep_version)
-        package_info["optionalDependencies"] = optional_dependencies
+        # convert v6 package dependencies + optionalDependencies
+        for key in ["dependencies", "optionalDependencies"]:
+            deps = package_info.get(key, None)
+            if deps != None:
+                dependencies = {}
+                for dep_name, dep_version in deps.items():
+                    dependencies[dep_name] = _convert_pnpm_v6_package_name(dep_version)
+                package_info[key] = dependencies
+
         result[_convert_pnpm_v6_package_name(package)] = package_info
     return result