Bug: WebUI data is loaded into each other twice

[Dark6846 4]

I had this error several times now. Unfortunately, my server is still quite underpowered at the moment, which i guess is certainly contributes to the error.

Error description:
Sometimes I click on movies or logs and the data takes a long time to load. I can't say exactly how, but by reloading or clicking on the same menu item again, the UI is then loaded twice and displayed one inside the other. This can be seen in the screenshot (I also have a video). Calling up the page via IP and port solves the error again directly.

Where does the error occur? WebUI
Which browser: Firefox 135.0.1 (64 bit)
Emby version: 4.8.10.0
OS: Linux (Ubuntu)
Where did I have the error: 'Logs' view and my movie list

[Luke 42077]

Hi, please attach the emby server log from when the problem occurred:

How to Report a Problem

Thanks.

[Dark6846 4]

4 minutes ago, Luke said:

Hi, please attach the emby server log from when the problem occurred:

How to Report a Problem

Thanks.

unfortunately it's been a few weeks and i don't know exactly which period. so i can't really give the log. if it occurs again, i'll be happy to give it. but i hope it won't be anymore, my server is way faster now.
I hope that it still helps.

[Happy2Play 9780]

I have seen issues like this randomly and a page refresh resolves it but have never been able to effectively reproduce it.

[Dark6846 4]

6 minutes ago, Happy2Play said:

I have seen issues like this randomly and a page refresh resolves it but have never been able to effectively reproduce it.

i just tried to reproduce it again, but i was not able to^^

[Happy2Play 9780]

On 3/4/2025 at 3:20 PM, Luke said:

Hi, please attach the emby server log from when the problem occurred:

How to Report a Problem

Thanks.

It is random and I think usually close to startup but a refresh always clears the previous page overlapping.

embyserver2.txt

[Dark6846 4]

On 3/5/2025 at 12:20 AM, Luke said:

Hi, please attach the emby server log from when the problem occurred:

How to Report a Problem

Thanks.

Same problem in a newly installed system.
Emby Version: 4.8.11.0

Edited September 21, 2025 by Dark6846

[Happy2Play 9780]

2 hours ago, Dark6846 said:

Same problem in a newly installed system.
Emby Version: 4.8.11.0

is it reproduceable after refreshing the page?

[Dark6846 4]

13 minutes ago, Happy2Play said:

is it reproduceable after refreshing the page?

No, unfortunately not.

[brothom 177]

@Happy2Playit looks to me as if the page content is rendered twice due to invalid HTML. Perhaps this has more to do with a specific template within Emby that isn't rendered fully or a template is still rendering / being fetched from the server while another render takes place.

@Dark6846does this happen on ALL pages or just specific ones? Does this issue occur more on certain pages than other and if so, which ones?

Addendum

I have found ONE way to reproduce this:

1. Go to the home screen and view a card (show, resume, doesn't matter or view any card in any slider or section for that matter)
2. Open the devtools (F12) and look for the button called "cardContent-button"
3. Rightclick the button and select "Store as global variable" in the contextmenu (it should now be available as the variable `temp1`)
4. Go to the console and execute: "temp1.click();temp1.click();"
5. On the new page, scroll: the content is now rendered twice

Edited September 22, 2025 by brothom

[Dark6846 4]

20 hours ago, brothom said:

@Happy2Playit looks to me as if the page content is rendered twice due to invalid HTML. Perhaps this has more to do with a specific template within Emby that isn't rendered fully or a template is still rendering / being fetched from the server while another render takes place.

@Dark6846does this happen on ALL pages or just specific ones? Does this issue occur more on certain pages than other and if so, which ones?

Addendum

I have found ONE way to reproduce this:

1. Go to the home screen and view a card (show, resume, doesn't matter or view any card in any slider or section for that matter)
2. Open the devtools (F12) and look for the button called "cardContent-button"
3. Rightclick the button and select "Store as global variable" in the contextmenu (it should now be available as the variable `temp1`)
4. Go to the console and execute: "temp1.click();temp1.click();"
5. On the new page, scroll: the content is now rendered twice

I had this problem more often when my server had even less power. This meant that requests sometimes took longer to load. Since I have little patience, I clicked on it several times, which I think led to the error.
Now I had reinstalled my server with more up-to-date hardware, and there was a moment when it took longer to load again (I was just scanning the media library). That's when the error occurred again.

I also assume that the HTML is rendered twice.

To answer your question:
This happens on different pages. It occurred for me in the log details, on the home page where all the movies are, and in the settings under “Overview.”

[brothom 177]

45 minutes ago, Dark6846 said:

I had this problem more often when my server had even less power. This meant that requests sometimes took longer to load. Since I have little patience, I clicked on it several times, which I think led to the error.

That's what I expected and makes sense how I was able to reproduce it mysqlf using:

21 hours ago, brothom said:

I have found ONE way to reproduce this:

1. Go to the home screen and view a card (show, resume, doesn't matter or view any card in any slider or section for that matter)
2. Open the devtools (F12) and look for the button called "cardContent-button"
3. Rightclick the button and select "Store as global variable" in the contextmenu (it should now be available as the variable `temp1`)
4. Go to the console and execute: "temp1.click();temp1.click();"
5. On the new page, scroll: the content is now rendered twice

There should be a failsafe or whatever in the web renderer to prevent this from happening though. When working with stuff like this, something called a `Promise` can be used. When a render request is already made, a `Promise` is created that, when another render is requested while the `Promise` is rendering, the previous `Promise` is cancelled and the new request gets a new active `Promise`.

For developers:

let renderPromiseReject = null;

async function render() {
    return new Promise((resolve, reject) => {
        // a rejector exists
        if (renderPromiseReject) {
            renderPromiseReject();
        }

        renderPromiseReject = reject;

        // do render magic
        // rendering is done

        renderPromiseReject = null;
        resolve();
    });
}

 

Edited September 23, 2025 by brothom