diff --git a/api/cefpython.md b/api/cefpython.md
index fe36900a..dd868d00 100644
--- a/api/cefpython.md
+++ b/api/cefpython.md
@@ -237,8 +237,6 @@ Description from upstream CEF:
 
 Post a task for execution on the thread associated with this task runner. Execution will occur asynchronously. Only Browser process threads are allowed.
 
-An example usage is in the wxpython.py example on Windows, in implementation of LifespanHandler.OnBeforePopup().
-
 List of threads in the Browser process:
 * cef.TID_UI: The main thread in the browser. This will be the same as the main application thread if cefpython.Initialize() is called with a ApplicationSettings.multi_threaded_message_loop value of false. Do not perform blocking tasks on this thread. All tasks posted after CefBrowserProcessHandler::OnContextInitialized() and before CefShutdown() are guaranteed to run. This thread will outlive all other CEF threads.
 * cef.TID_DB: Used to interact with the database.
diff --git a/docs/Migration-guide.md b/docs/Migration-guide.md
index 435ea6e9..e6b804ce 100644
--- a/docs/Migration-guide.md
+++ b/docs/Migration-guide.md
@@ -36,8 +36,9 @@ Table of contents:
 * [v55.3+ Handlers' callbacks and other interfaces](#v553-handlers-callbacks-and-other-interfaces)
 * [v56+ MacOS 10.9+ required to run](#v56-macos-109-required-to-run)
 * [v57.1+ High DPI support on Windows](#v571-high-dpi-support-on-windows)
-* [v66.0+ Linux patch that fixed HTTPS cache problems on pages with certificate errors was disabled](#v660-linux-patch-that-fixed-https-cache-problems-on-pages-with-certificate-errors-was-disabled)
-* [v66.0+ DisplayHandler.OnConsoleMessage new param 'level'](#v660-displayhandleronconsolemessage-new-param-level)
+* [v66+ Linux patch that fixed HTTPS cache problems on pages with certificate errors was disabled](#v66-linux-patch-that-fixed-https-cache-problems-on-pages-with-certificate-errors-was-disabled)
+* [v66+ DisplayHandler.OnConsoleMessage has new param 'level'](#v66-displayhandleronconsolemessage-has-new-param-level)
+* [v66+ LifespanHandler.OnBeforePopup is now called on UI thread](#v66-lifespanhandleronbeforepopup-is-now-called-on-ui-thread)
 
 
 
@@ -298,15 +299,24 @@ for High DPI support. In previous versions the default value was
 "system_dpi" and if you have set it explicitilly in your application,
 then you should change it to an empty string now.
 
-## v66.0+ Linux patch that fixed HTTPS cache problems on pages with certificate errors was disabled
+
+## v66+ Linux patch that fixed HTTPS cache problems on pages with certificate errors was disabled
 
 That patch allowed for HTTPS caching to work when using self-signed
-certificates (or any invalid certificate). This doesn't work anymore. See
-Issue [#125](../../../issues/125) for more details.
+certificates (or any invalid certificate). This doesn't work anymore.
+If you need this feature then you can build from sources and apply
+the patch yourself. See Issue [#125](../../../issues/125) for more details.
 
 
-## v66.0+ DisplayHandler.OnConsoleMessage new param 'level'
+## v66+ DisplayHandler.OnConsoleMessage has new param 'level'
 
 The DisplayHandler.[OnConsoleMessage](../api/DisplayHandler.md#onconsolemessage)
 callback has a new param `level`.
 
+
+## v66+ LifespanHandler.OnBeforePopup is now called on UI thread
+
+The LifespanHandler.[OnBeforePopup](../api/LifespanHandler.md#onbeforepopup)
+callback is now called on UI thread. Previously it was called on
+IO thread.
+
diff --git a/src/cef_v59..v66_changes.txt b/src/cef_v59..v66_changes.txt
index e710e4ac..1f1513b7 100644
--- a/src/cef_v59..v66_changes.txt
+++ b/src/cef_v59..v66_changes.txt
@@ -7,10 +7,10 @@ BREAKAGE (needs updating Migration Guide doc)
 - + OnConsoleMessage: new param 'level'
 - + update migration guide
 
-cef_life_span_handler.h
-- OnBeforePopup: created on UI thread instead of IO thread
-  - update checks for thread
-  - update migration guide
++ cef_life_span_handler.h
+- + OnBeforePopup: created on UI thread instead of IO thread
+  - + update checks for thread
+  - + update migration guide
 
 cef_print_handler.h
 - Modify subprocess/print_handler_gtk.h and .cpp files
diff --git a/src/client_handler/lifespan_handler.cpp b/src/client_handler/lifespan_handler.cpp
index d54f5f0a..b4d7d52f 100644
--- a/src/client_handler/lifespan_handler.cpp
+++ b/src/client_handler/lifespan_handler.cpp
@@ -21,7 +21,7 @@ bool LifespanHandler::OnBeforePopup(CefRefPtr<CefBrowser> browser,
                                     CefBrowserSettings& settings,
                                     bool* no_javascript_access)
 {
-    REQUIRE_IO_THREAD();
+    REQUIRE_UI_THREAD();
     // Note: passing popupFeatures is not yet supported.
     const int popupFeaturesNotImpl = 0;
     return LifespanHandler_OnBeforePopup(browser, frame, target_url,