After running a while, localhost connection refused

[Linslv77]

I have a program that opens a WebUI window and continuously calls JavaScript to update its contents. It works perfectly on my notebook, but when I run it on another notebook, I encounter "localhost connection refused" after about an hour. What could be causing this issue?

I want to work around this issue by reopening the WebUI window. However, when I call close() and sleep for 3 seconds, then call show() to reopen, I get "Access Denied". What is the correct way to reopen a window?

PS: The full message on the "Access Denied" page is:
Access Denied
You can't access this content
because it's already in use in
another window.

Thanks a lot for your help.

[AlbertShown]

This sounds like a power management issue by OS.

I think you are using a web-browser-based window, and we know that browsers kill the WebSocket connection if no activity after 2 minutes, so, WebUI get around that by sending a ping every 30 seconds.

However, now, seems like after an hour, your OS goes to sleep or something, and that make web browser cut/kill all WebSocket active connections in all web sites regardless of its active or not... therefor, all web sites need to re-connect to the server again.

We need to find a way to force browser to not kill WebSocket connection. Or we need to figure out how to make WebUI distinguish between a WebSocket close even because simply the user closed the window, and between close even because OS/Browser killed all active connections to save power.

[AlbertShown]

Reported here #584

[AlbertShown]

A Quick around for you is to use WebView based window instead of web browser.

[AlbertShown]

Access Denied after calling close() looks like a bug, WebUI does not receive close even because web browser already killed that connection to save power. But this is easy to fix, please let me look into that.

[Linslv77]

Thank you, AlbertShown.

Here is more information about my development environment. I use WebUI 2.5.0-beta.3 binary: webui-windows-msvc-x64.zip, the static version library.

Now, I have started using the debug version to get more information and try your quick around.

[AlbertShown]

try my_window.show_ws()

[AlbertShown]

You did nothing wrong. it's just known issues that get resolved in beta and nightly build.
I recommend you do this:

git clone https://github.com/webui-dev/webui.git
cd webui
nmake debug
nmake

Then try using the debug version of static library webui\dist\debug\webui-2-static.lib.

If you want release version then just use webui\dist\webui-2-static.lib

[AlbertShown]

It will be helpful if you create a new issue and share the logs so we can know if it's a new issue, or if it's already solved.

[Linslv77]

Sorry, did you mean show_wv()?

My project currently uses only CMakeLists.txt for building. It seems like importing WebView would require some work (like switching to csproj), so I think I’ll work around with v2.4.2 for now.

Also, I won’t be using my work computer for the next two days. I’ll get back to you after that.

[AlbertShown]

My bad, yes, I mean show_wv().

About WebView, no worries, WebUI use COM APIs to dynamically load WebView runtime, therefore when you build WebUI from source nmake you don't need to add/reference any external WebView library or header or switching to csproj or anything.

When you run your final program, if you use show_wv() it will look up for official WebView2Loader DLL to dynamically tries to load WebView.

However, you can still use web browser window, and this OS power management issue that cut the WebSocket will be solved next week.

[Linslv77]

Hi, I uploaded the logs: #585
And I tested show_wv but I think it still use my browser:
[Core] _webui_show_window() -> WebView Not Found
[Core] _webui_browser_start([http://localhost:38372/test.html], [1])
[Core] _webui_find_the_best_browser()
[Core] _webui_is_process_running([chrome.exe])
[Core] _webui_is_process_running([msedge.exe])
[Core] _webui_browser_exist([4])...
Even I had manually install WebView2 (https://developer.microsoft.com/en-us/microsoft-edge/webview2?form=MA13LH#download
Hope this info can help.

[Linslv77]

Thanks for the explanation!
Please refer the attachment.
webui_test-Nightly build-show_wv-20250417.txt
I use webui.hpp and there is a global webui::window object. So it comes an initialization before my program starting (msg: Hello, from webui_test!).

[AlbertShown]

Based on logs, I think WebUI fails at _webui.webviewLib = LoadLibraryA("WebView2Loader.dll");.
The issue in in your WebView installation, not WebUI. I have a feeling that if you created a minimal Win32 WebView2 (without WebUI) example it won't work either.

Please try this:

• Go to https://www.nuget.org/packages/microsoft.web.webview2
• Click on Download package
• Rename microsoft.web.webview2.1.0.3179.45.nupkg to microsoft.web.webview2.1.0.3179.45.zip
• Extract microsoft.web.webview2.1.0.3179.45.zip
• Goto microsoft.web.webview2.1.0.3179.45\build\native\x64 (or x86, arm64)
• Copy WebView2Loader.dll
• Paste WebView2Loader.dll in the same folder as your executable
• Run your program again

[Linslv77]

Wow, it works! Thank you.
I will continue testing to see if connection refused no longer occurs.

And, when I test with nightly build and show_wv, the reopen issue still happens (no window appears as I posted last week). Is it a known issue?

[hassandraga]

Hi @Linslv77, please open a new issue and share the complete logs of the reopen procedure.

[Linslv77]

Hi hassandraga,
It is the same issue with #585 , so I upload the new log in it. Please refer the last attachment.