diff --git a/src/fwl_io/mirror.py b/src/fwl_io/mirror.py
index b244dd4..3079d56 100644
--- a/src/fwl_io/mirror.py
+++ b/src/fwl_io/mirror.py
@@ -151,20 +151,32 @@ def _request(self, method: str, path: str, **kwargs) -> dict:
                 timeout=self.timeout,
                 **kwargs,
             )
-            if not response.ok:
-                raise DataverseError(
-                    f'Dataverse {method} {path} failed ({response.status_code}): '
-                    f'{response.text[:500]}'
-                )
-            return response.json()
         except requests.RequestException as exc:
-            # A transport failure (connection error, timeout, DNS) or an
-            # unparseable response body (JSONDecodeError is a requests error) is
-            # a failed native-API request too; surface it as a DataverseError so
-            # every Dataverse-side failure is one error type for callers to catch.
-            # The not-ok DataverseError above is not a RequestException, so it
-            # passes through this handler unchanged.
+            # A transport failure (connection error, timeout, DNS) is a failed
+            # native-API request too; surface it as a DataverseError so every
+            # Dataverse-side failure is one error type for callers to catch.
             raise DataverseError(f'Dataverse {method} {path} failed: {exc}') from exc
+        if not response.ok:
+            raise DataverseError(
+                f'Dataverse {method} {path} failed ({response.status_code}): {response.text[:500]}'
+            )
+        if not response.content:
+            # A 2xx with an empty body (routine for a DELETE) is a success
+            # with nothing to parse.
+            return {}
+        try:
+            body = response.json()
+        except ValueError:
+            raise DataverseError(
+                f'Dataverse {method} {path} returned {response.status_code} with a '
+                f'non-JSON body: {response.text[:500]}'
+            ) from None
+        if not isinstance(body, dict):
+            raise DataverseError(
+                f'Dataverse {method} {path} returned {response.status_code} with a '
+                f'non-object JSON body: {response.text[:500]}'
+            )
+        return body
 
     def _post(self, path: str, **kwargs) -> dict:
         return self._request('POST', path, **kwargs)
@@ -294,9 +306,10 @@ def mirror_to_dataverse(
     DataverseError
         If a Dataverse native-API request fails: the server rejects it (for
         example an unknown subject in the citation metadata), the HTTP transport
-        fails (connection error or timeout), or the response body is unparseable.
-        A failure during upload or publish can leave a draft that the rollback
-        then tries to delete.
+        fails (connection error or timeout), or a 2xx response body is not a
+        JSON object (a non-empty body that fails to parse, or that parses to
+        something other than a JSON object). A failure during upload or publish
+        can leave a draft that the rollback then tries to delete.
     DownloadError
         If a Zenodo file fails its checksum or cannot be downloaded; raised by
         the fetcher (``fwl_io.fetch``) before any Dataverse write.
diff --git a/tests/test_mirror.py b/tests/test_mirror.py
index 9cc5362..dc4e0a7 100644
--- a/tests/test_mirror.py
+++ b/tests/test_mirror.py
@@ -352,27 +352,162 @@ def boom(*args, **kwargs):
         requests.request = orig
 
 
+def _fake_response(status_code: int, content: bytes):
+    import requests
+
+    response = requests.Response()
+    response.status_code = status_code
+    response._content = content
+    return response
+
+
 @pytest.mark.unit
-def test_unparseable_success_body_becomes_a_dataverse_error():
-    """A 2xx response with a non-JSON body is wrapped as DataverseError too.
+def test_create_with_an_empty_success_body_raises_for_the_missing_persistent_id():
+    """A 2xx create response with an empty body still fails, for the missing id."""
+    import requests
 
-    JSONDecodeError is a requests error, so decoding a garbled success body would
-    otherwise leak a bare requests exception from a Dataverse call; every
-    Dataverse-side failure must surface as the one DataverseError type.
+    client = DataverseClient('http://unused', 'tok')
+    orig = requests.request
+    requests.request = lambda *args, **kwargs: _fake_response(200, b'')
+    try:
+        with pytest.raises(DataverseError, match='no persistentId'):
+            client.create_dataset('coll', {'datasetVersion': {}})
+    finally:
+        requests.request = orig
+
+
+@pytest.mark.unit
+def test_create_with_a_non_json_success_body_raises_with_the_status_and_body():
+    """A 2xx create response with a non-JSON body raises, naming the status and body.
+
+    This is the exact shape a live Dataverse.nl call returned: a 2xx status with
+    a body that failed to parse as JSON. The status code and raw body must be in
+    the exception message, not just discoverable by decoding the JSON error text.
     """
     import requests
 
-    response = requests.Response()
-    response.status_code = 200  # ok, so it reaches the body decode
-    response._content = b'this is not json'
     client = DataverseClient('http://unused', 'tok')
     orig = requests.request
-    requests.request = lambda *args, **kwargs: response
+    requests.request = lambda *args, **kwargs: _fake_response(200, b'this is not json')
     try:
-        with pytest.raises(DataverseError, match='failed') as exc_info:
+        with pytest.raises(DataverseError, match='this is not json') as exc_info:
             client.create_dataset('coll', {'datasetVersion': {}})
-        # The decode error is a requests error, chained as the cause.
-        assert isinstance(exc_info.value.__cause__, requests.RequestException)
+        assert '200' in str(exc_info.value)
+    finally:
+        requests.request = orig
+
+
+@pytest.mark.unit
+def test_create_with_a_non_object_json_body_raises_with_the_status_and_body():
+    """A 2xx create response whose body parses to a non-object (e.g. null) raises.
+
+    ``response.json()`` succeeds here, so this must be checked separately from
+    the decode failure above; a caller must never see a bare AttributeError
+    from treating a non-dict body as a dict.
+    """
+    import requests
+
+    client = DataverseClient('http://unused', 'tok')
+    orig = requests.request
+    requests.request = lambda *args, **kwargs: _fake_response(200, b'null')
+    try:
+        with pytest.raises(DataverseError, match='non-object JSON body') as exc_info:
+            client.create_dataset('coll', {'datasetVersion': {}})
+        assert '200' in str(exc_info.value)
+    finally:
+        requests.request = orig
+
+
+@pytest.mark.unit
+def test_add_file_accepts_an_empty_success_body(tmp_path):
+    """add_file does not raise when Dataverse returns 2xx with an empty body."""
+    import requests
+
+    client = DataverseClient('http://unused', 'tok')
+    orig = requests.request
+    requests.request = lambda *args, **kwargs: _fake_response(200, b'')
+    target = tmp_path / 'f.dat'
+    target.write_bytes(b'data')
+    try:
+        client.add_file('doi:10.34894/DEMO01', target)  # must not raise
+    finally:
+        requests.request = orig
+
+
+@pytest.mark.unit
+def test_add_file_raises_with_the_status_and_body_on_a_non_json_success_body(tmp_path):
+    """add_file raises on a 2xx non-JSON body, naming the status and body."""
+    import requests
+
+    client = DataverseClient('http://unused', 'tok')
+    orig = requests.request
+    requests.request = lambda *args, **kwargs: _fake_response(200, b'this is not json')
+    target = tmp_path / 'f.dat'
+    target.write_bytes(b'data')
+    try:
+        with pytest.raises(DataverseError, match='this is not json') as exc_info:
+            client.add_file('doi:10.34894/DEMO01', target)
+        assert '200' in str(exc_info.value)
+    finally:
+        requests.request = orig
+
+
+@pytest.mark.unit
+def test_publish_accepts_an_empty_success_body():
+    """publish does not raise when Dataverse returns 2xx with an empty body."""
+    import requests
+
+    client = DataverseClient('http://unused', 'tok')
+    orig = requests.request
+    requests.request = lambda *args, **kwargs: _fake_response(200, b'')
+    try:
+        client.publish('doi:10.34894/DEMO01')  # must not raise
+    finally:
+        requests.request = orig
+
+
+@pytest.mark.unit
+def test_publish_raises_with_the_status_and_body_on_a_non_json_success_body():
+    """publish raises on a 2xx non-JSON body, naming the status and body."""
+    import requests
+
+    client = DataverseClient('http://unused', 'tok')
+    orig = requests.request
+    requests.request = lambda *args, **kwargs: _fake_response(200, b'this is not json')
+    try:
+        with pytest.raises(DataverseError, match='this is not json') as exc_info:
+            client.publish('doi:10.34894/DEMO01')
+        assert '200' in str(exc_info.value)
+    finally:
+        requests.request = orig
+
+
+@pytest.mark.unit
+def test_delete_draft_accepts_an_empty_success_body():
+    """delete_draft (the rollback path) does not raise when Dataverse returns an empty 2xx."""
+    import requests
+
+    client = DataverseClient('http://unused', 'tok')
+    orig = requests.request
+    requests.request = lambda *args, **kwargs: _fake_response(200, b'')
+    try:
+        client.delete_draft('doi:10.34894/DEMO01')  # must not raise
+    finally:
+        requests.request = orig
+
+
+@pytest.mark.unit
+def test_delete_draft_raises_with_the_status_and_body_on_a_non_json_success_body():
+    """delete_draft (the rollback path) raises on a 2xx non-JSON body, naming status and body."""
+    import requests
+
+    client = DataverseClient('http://unused', 'tok')
+    orig = requests.request
+    requests.request = lambda *args, **kwargs: _fake_response(200, b'this is not json')
+    try:
+        with pytest.raises(DataverseError, match='this is not json') as exc_info:
+            client.delete_draft('doi:10.34894/DEMO01')
+        assert '200' in str(exc_info.value)
     finally:
         requests.request = orig