Uncaught error from Chrome... This instance is already constructed

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1

I’ve been getting this error for about 2 weeks now, it fires everytime I refresh/reload a view or the view is refreshed/reloaded. I’m afraid it’s beyond my skillset to understand what it’s trying to tell me, I would appreciate any pointers in the right direction (or an answer if you have one).

Condensed Logs:
Logger: frontend.js.modern.202508111
Source: components/system_log/init.py:331
First occurred: September 1, 2025 at 7:58:18 PM (3 occurrences)
Last logged: September 1, 2025 at 8:57:58 PM

Uncaught error from Chrome 116.0.5845.140 on Windows 10 TypeError: Failed to construct ‘HTMLElement’: This instance is already constructed construct (src/scoped-custom-element-registry.ts:340:21) super (src/reactive-element.ts:1037:4) new i (src/lit-element.ts:130:) super (node_modules/@awesome.me/webawesome/dist/chunks/chunk.ETAGLSDL.js:19:4) super (node_modules/@awesome.me/webawesome/dist/chunks/chunk.I5CT6KOH.js:21:4) N (src/scoped-custom-element-registry.ts:645:4) J (src/scoped-custom-element-registry.ts:408:8) importNode (src/lit-html.ts:1218:51) u (src/lit-html.ts:1639:32) $ (src/lit-html.ts:1475:11)

Raw Logs:


TypeError: Failed to construct 'HTMLElement': This instance is already constructed

construct (src/scoped-custom-element-registry.ts:340:21)

super (src/reactive-element.ts:1037:4)

new i (src/lit-element.ts:130:)

super (node_modules/@awesome.me/webawesome/dist/chunks/chunk.ETAGLSDL.js:19:4)

super (node_modules/@awesome.me/webawesome/dist/chunks/chunk.I5CT6KOH.js:21:4)

N (src/scoped-custom-element-registry.ts:645:4)

J (src/scoped-custom-element-registry.ts:408:8)

importNode (src/lit-html.ts:1218:51)

u (src/lit-html.ts:1639:32)

$ (src/lit-html.ts:1475:11)
3 Likes
2

Have the same warning. Don’t know what is it…

3

Currently I’m suspicious of Browser Mod for this error but I haven’t had a chance to test that theory out yet, that’s this weekends chore.

4

Likely Frontend issue TypeError: Failed to construct 'HTMLElement' - WebView/Android · Issue #26919 · home-assistant/frontend · GitHub. ha-fade-in was recently migrated to use webawesome so issue would have come in at that time.

Browser Mod 2.5.2 did have a similar console error but only on touch devices when tapping interact. This was corrected in 2.5.3. Also to note that Browser Mod does not use webawesome directly in any way.

5

I see, thanks for that. The posts in that thread all seem to be using android though and I’m using Iridium browser (which has developed its own annoying issues recently) on a desktop. FWIW I wasn’t ready to point fingers yet, it was just a suspicion as Browser Mod is so front end heavy… I am on 2.5.3 and still get the error. Thanks for all your work on Browser Mod BTW.

I’ll update this thread once I have time to investigate (AKA poke it with a stick) this weekend.

1 Like
6

Sounds good. I have picked up so many speculations on Browser Mod recently, but it is rarely the issue. It somehow has got a poor name probably because of past issues with many devices etc. All these are now ancient history.

The trace you show is very similar to the issue I posted, especially that webawesome is in the stack.

I am not sure what you mean by Browser Mod being front end heavy. You could say that for card-mod. Browser Mod apllies some Frontend settings in a light way, then just sits there waiting for service commands and responding to activty to update server, but not much at all.

7

Confirming that HA in safe mode still throws the error, it is definitely a frontend issue and has nothing to do with Browser Mod or any other custom integration/card/whatever.

Thanks for pointing the actual issue out for me @dcapslock, much appreciated.

1 Like