Merge pull request #4074 from b84330808/fix-pages-pathname-decoding

Decode the pages router pathname before matching it

Author: T4rk1n

CHANGELOG.md

@@ -59,6 +59,7 @@ This project adheres to [Semantic Versioning](https://semver.org/).
 - [#4023](https://github.com/plotly/dash/pull/4023) Fix extra callback registrations when an app runs from the parent directory: `python app/app.py`, where the script shares its folder's name, registered its callbacks twice, and `python app/main.py` imported a sibling `app/app.py` as the parent package and registered its callbacks too (regression introduced in 4.4.1 by [#3883](https://github.com/plotly/dash/pull/3883)). Fixes [#4011](https://github.com/plotly/dash/issues/4011).
 - [#4057](https://github.com/plotly/dash/pull/4057) Fixed background callbacks to update `set_props` instead of replacing. Fixes [#3104](https://github.com/plotly/dash/issues/3104).
 - [#3923](https://github.com/plotly/dash/pull/3923) Fix a blank page and `SyntaxError` in the browser when a dict component ID has a dot in one of its values. Fixes [#3480](https://github.com/plotly/dash/issues/3480).
+- [#4074](https://github.com/plotly/dash/pull/4074) Fix Pages passing percent-encoded path variables to `layout` and `title`, and the 404 page for paths with spaces or non-ASCII characters. Fixes [#2360](https://github.com/plotly/dash/issues/2360).
 - [#4012](https://github.com/plotly/dash/pull/4012) Fix `InvalidCallbackReturnValue` raised when a no-output background callback's error handler returns `None` (or the job is cancelled), by treating `None` returns from error handlers and the cancelled-job branch the same way — as `NoUpdate()` only when there are outputs, `None` otherwise. Fixes [#3628](https://github.com/plotly/dash/issues/3628).
 
 ## [4.4.1] - 2026-07-21

dash/dash.py

@@ -17,7 +17,7 @@
 import mimetypes
 import hashlib
 import base64
-from urllib.parse import urlparse
+from urllib.parse import unquote, urlparse
 from typing import (
     Any,
     Callable,
@@ -2851,7 +2851,9 @@ async def router_async():
                 async def update(pathname_, search_, **states):
                     query_parameters = _parse_query_string(search_)
                     page, path_variables = _path_to_page(
-                        self.strip_relative_path(pathname_)
+                        self.strip_relative_path(
+                            unquote(pathname_) if pathname_ else pathname_
+                        )
                     )
                     if page == {}:
                         for module, page in _pages.PAGE_REGISTRY.items():
@@ -2939,7 +2941,9 @@ def router_sync():
                 def update(pathname_, search_, **states):
                     query_parameters = _parse_query_string(search_)
                     page, path_variables = _path_to_page(
-                        self.strip_relative_path(pathname_)
+                        self.strip_relative_path(
+                            unquote(pathname_) if pathname_ else pathname_
+                        )
                     )
                     if page == {}:
                         for module, page in _pages.PAGE_REGISTRY.items():

tests/unit/pages/test_pages.py

@@ -2,7 +2,7 @@
 
 import pytest
 import dash
-from dash import Dash, _pages
+from dash import Dash, _pages, html
 from mock import patch
 
 
@@ -76,3 +76,49 @@ def test_import_layouts_from_pages(
 
     page_entry = list(dash.page_registry.values())[0]
     assert page_entry["module"] == expected_module_name
+
+
+def _route(client, pathname):
+    response = client.post(
+        "/_dash-update-component",
+        json={
+            "output": ".._pages_content.children..._pages_store.data..",
+            "outputs": [
+                {"id": "_pages_content", "property": "children"},
+                {"id": "_pages_store", "property": "data"},
+            ],
+            "inputs": [
+                {"id": "_pages_location", "property": "pathname", "value": pathname},
+                {"id": "_pages_location", "property": "search", "value": ""},
+            ],
+            "state": [],
+            "changedPropIds": ["_pages_location.pathname"],
+        },
+    )
+    return response.get_json()["response"]["_pages_content"]["children"]
+
+
+@pytest.mark.parametrize("use_async", [False, True])
+def test_router_decodes_pathname(clear_pages_state, use_async):
+    if use_async:
+        pytest.importorskip("asgiref")
+    app = Dash(__name__, use_pages=True, pages_folder="", use_async=use_async)
+    dash.register_page(
+        "report",
+        path_template="/report/<name>",
+        layout=lambda name=None, **_: html.Div(name, id="name"),
+    )
+    dash.register_page("cafe", path="/caf\u00e9", layout=html.Div(id="cafe"))
+    app.layout = html.Div(dash.page_container)
+    client = app.server.test_client()
+    client.get("/")
+
+    # dcc.Location sends window.location.pathname, which browsers percent-encode
+    assert _route(client, "/report/hello%20world")["props"]["children"] == (
+        "hello world"
+    )
+    assert _route(client, "/report/%E6%97%A5%E6%9C%AC")["props"]["children"] == (
+        "\u65e5\u672c"
+    )
+    assert _route(client, "/report/a%0Ab")["props"]["children"] == "a\nb"
+    assert _route(client, "/caf%C3%A9")["props"]["id"] == "cafe"