Get Warning: Some icons were re-registered. Applications should only call registerIcons for any given icon once

[Mengting233]

Node version: v18.17.1 SPFx version: 1.18.2 Instruction: https://learn.microsoft.com/en-us/sharepoint/dev/spfx/extensions/get-started/using-page-placeholder-with-extensions

I followed the instruction and served the extension, but the warning icon is not showing. I get the warning in console below:

Some icons were re-registered. Applications should only call registerIcons for any given icon once. Redefining what an icon is may have unintended consequences. Duplicates include: GlobalNavButton, ChevronDown, ChevronUp, Edit, Add, Cancel, More, Settings, Mail, Filter (+ 1756 more)

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Document Details

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• ID: f0ecfb7b-2d99-1835-1688-8fbb904fcc8c
• Version Independent ID: 9001961c-5199-76ca-c3a7-b3d69b49e20d
• Content: Use page placeholders from Application Customizer (Hello World part 2)
• Content Source: docs/spfx/extensions/get-started/using-page-placeholder-with-extensions.md
• Service: sharepoint-online
• Sub-service: sharepoint-framework
• GitHub Login: @VesaJuvonen
• Microsoft Alias: vesaj

[kbeeveer46]

It may not be your code that's causing this. It also shows this warning on a blank workbench page when you click the plus sign to add a web part to the page. Either clicking on the plus sign icon or when the pop up appears with the list of web parts causes this warning, as well, and it's been there for years. Since Microsoft's own code causes this warning in that instance it may be their code causing the warning in your instance, as well.