diff --git a/swh/loader/package/npm/loader.py b/swh/loader/package/npm/loader.py
--- a/swh/loader/package/npm/loader.py
+++ b/swh/loader/package/npm/loader.py
@@ -89,7 +89,16 @@
         # metadata, using the version number that the API claims this package
         # has.
         extrinsic_version = a_metadata['version']
-        date = self.info['time'][extrinsic_version]
+
+        if 'time' in self.info:
+            date = self.info['time'][extrinsic_version]
+        else:
+            artifact_name = os.path.basename(a_metadata['dist']['tarball'])
+            raise ValueError(
+                'Origin %s: Cannot determine upload time for artifact %s.' %
+                (self.url, artifact_name)
+            )
+
         date = iso8601.parse_date(date)
         date = normalize_timestamp(int(date.timestamp()))
 
diff --git a/swh/loader/package/npm/tests/data/https_replicate.npmjs.com/jammit-no-time b/swh/loader/package/npm/tests/data/https_replicate.npmjs.com/jammit-no-time
new file mode 100644
--- /dev/null
+++ b/swh/loader/package/npm/tests/data/https_replicate.npmjs.com/jammit-no-time
@@ -0,0 +1,76 @@
+{
+  "_id": "jammit-express",
+  "_rev": "1-ffa3f96992e5e31dd29df779dc771e84",
+  "name": "jammit-express",
+  "description": "Jammit Helpers for Express.js",
+  "dist-tags": {
+    "latest": "0.0.1"
+  },
+  "versions": {
+    "0.0.1": {
+      "name": "jammit-express",
+      "version": "0.0.1",
+      "description": "Jammit Helpers for Express.js",
+      "author": {
+        "name": "Eric Abouaf",
+        "email": "eric.abouaf@mail.com"
+      },
+      "bugs": {
+        "web": "http://github.com/neyric/jammit-express/issues"
+      },
+      "os": [
+        "darwin",
+        "linux"
+      ],
+      "contributors": [
+        {
+          "name": "Eric Abouaf",
+          "email": "eric.abouaf@mail.com",
+          "url": "http://neyric.com"
+        }
+      ],
+      "engines": {
+        "node": ">=0.2.0"
+      },
+      "directories": {
+        "lib": "lib"
+      },
+      "main": "./init",
+      "bin": null,
+      "dependencies": null,
+      "licenses": [
+        {
+          "type": "BSD"
+        }
+      ],
+      "repository": {
+        "type": "git",
+        "url": "http://github.com/neyric/jammit-express.git"
+      },
+      "_id": "jammit-express@0.0.1",
+      "_nodeSupported": true,
+      "_npmVersion": "0.2.7-2",
+      "_nodeVersion": "v0.3.1-pre",
+      "dist": {
+        "tarball": "https://registry.npmjs.org/jammit-express/-/jammit-express-0.0.1.tgz",
+        "shasum": "10927257f0512af082200a91e24d9ec9cccedbba"
+      }
+    }
+  },
+  "maintainers": [
+    {
+      "name": "neyric",
+      "email": "eric.abouaf@mail.com"
+    }
+  ],
+  "author": {
+    "name": "Eric Abouaf",
+    "email": "eric.abouaf@mail.com"
+  },
+  "repository": {
+    "type": "git",
+    "url": "http://github.com/neyric/jammit-express.git"
+  },
+  "readme": "",
+  "readmeFilename": ""
+}
diff --git a/swh/loader/package/npm/tests/test_npm.py b/swh/loader/package/npm/tests/test_npm.py
--- a/swh/loader/package/npm/tests/test_npm.py
+++ b/swh/loader/package/npm/tests/test_npm.py
@@ -533,3 +533,26 @@
     origin_visit = list(loader.storage.origin_visit_get(url))[-1]
     assert origin_visit['status'] == 'full'
     assert origin_visit['type'] == 'npm'
+
+
+def test_npm_artifact_with_no_upload_time(swh_config, requests_mock_datadir):
+    """With no time upload, artifact is skipped
+
+    """
+    package = 'jammit-no-time'
+    url = package_url(package)
+    loader = NpmLoader(url)
+
+    actual_load_status = loader.load()
+    assert actual_load_status['status'] == 'failed'
+
+    # no branch as one artifact without any intrinsic metadata
+    expected_snapshot = {
+        'id': '1a8893e6a86f444e8be8e7bda6cb34fb1735a00e',
+        'branches': {},
+    }
+    check_snapshot(expected_snapshot, loader.storage)
+
+    origin_visit = list(loader.storage.origin_visit_get(url))[-1]
+    assert origin_visit['status'] == 'partial'
+    assert origin_visit['type'] == 'npm'