diff --git a/panel/io/state.py b/panel/io/state.py
index d7b3eb0e75..0685f32c40 100644
--- a/panel/io/state.py
+++ b/panel/io/state.py
@@ -156,7 +156,7 @@ def _thread_id(self, thread_id):
     def _unblocked(self, doc):
         thread = threading.current_thread()
         thread_id = thread.ident if thread else None
-        return doc is self.curdoc and self._thread_id == thread_id
+        return doc is self.curdoc and self._thread_id in (thread_id, None)
 
     @param.depends('busy', watch=True)
     def _update_busy(self):
diff --git a/panel/reactive.py b/panel/reactive.py
index 3b73f761cd..1e358b4ab2 100644
--- a/panel/reactive.py
+++ b/panel/reactive.py
@@ -20,12 +20,11 @@
 from bokeh.models import LayoutDOM
 from bokeh.model import DataModel
 from param.parameterized import ParameterizedMetaclass, Watcher
-from tornado import gen
 
 from .io.model import hold
 from .io.notebook import push
 from .io.server import unlocked
-from .io.state import state
+from .io.state import set_curdoc, state
 from .models.reactive_html import (
     ReactiveHTML as _BkReactiveHTML, ReactiveHTMLParser
 )
@@ -278,19 +277,19 @@ def _process_events(self, events):
             with edit_readonly(state):
                 state.busy = busy
 
-    @gen.coroutine
-    def _change_coroutine(self, doc=None):
+    async def _change_coroutine(self, doc=None):
         if state._thread_pool:
             state._thread_pool.submit(self._change_event, doc)
         else:
-            self._change_event(doc)
+            with set_curdoc(doc):
+                self._change_event(doc)
 
-    @gen.coroutine
-    def _event_coroutine(self, event):
+    async def _event_coroutine(self, event, doc):
         if state._thread_pool:
             state._thread_pool.submit(self._process_event, event)
         else:
-            self._process_event(event)
+            with set_curdoc(doc):
+                self._process_event(event)
 
     def _change_event(self, doc=None):
         try:
@@ -325,12 +324,12 @@ def _comm_event(self, event):
             self._process_event(event)
 
     def _server_event(self, doc, event):
-        if doc.session_context:
+        if doc.session_context and not state._unblocked(doc):
             doc.add_next_tick_callback(
-                partial(self._event_coroutine, event)
+                partial(self._event_coroutine, event, doc)
             )
         else:
-            self._process_event(event)
+            self._comm_event(event)
 
     def _server_change(self, doc, ref, subpath, attr, old, new):
         if subpath:
diff --git a/panel/tests/pane/test_image.py b/panel/tests/pane/test_image.py
index e9d1f42850..20d446d1d5 100644
--- a/panel/tests/pane/test_image.py
+++ b/panel/tests/pane/test_image.py
@@ -89,7 +89,7 @@ def test_load_from_stringio():
 
 def test_loading_a_image_from_url():
     """Tests the loading of a image from a url"""
-    url = 'https://file-examples-com.github.io/uploads/2017/10/file_example_PNG_500kB.png'
+    url = 'https://raw.githubusercontent.com/holoviz/panel/master/doc/_static/logo.png'
 
     image_pane = PNG(url)
     image_data = image_pane._data()
@@ -114,7 +114,7 @@ def test_loading_a_image_from_pathlib():
 
 def test_image_alt_text(document, comm):
     """Tests the loading of a image from a url"""
-    url = 'https://file-examples-com.github.io/uploads/2017/10/file_example_PNG_500kB.png'
+    url = 'https://raw.githubusercontent.com/holoviz/panel/master/doc/_static/logo.png'
 
     image_pane = PNG(url, embed=False, alt_text="Some alt text")
     model = image_pane.get_root(document, comm)
@@ -124,7 +124,7 @@ def test_image_alt_text(document, comm):
 
 def test_image_link_url(document, comm):
     """Tests the loading of a image from a url"""
-    url = 'https://file-examples-com.github.io/uploads/2017/10/file_example_PNG_500kB.png'
+    url = 'https://raw.githubusercontent.com/holoviz/panel/master/doc/_static/logo.png'
 
     image_pane = PNG(url, embed=False, link_url="http://anaconda.org")
     model = image_pane.get_root(document, comm)