topic Re: How to add the allow-downloads flag to the sandbox tag in iframe in APIs & Integrations

How to add the allow-downloads flag to the sandbox tag in iframe

eduardoavargas — Wed, 27 May 2020 18:32:33 GMT

With the last update of chrome it restricted the possibility to download in a restricted iframe, see the note (https://www.chromestatus.com/feature/5706745674465280)

I have an integration where I make files available for download, now how can I add this flag to an iframe of the crm card extension

Re: How to add the allow-downloads flag to the sandbox tag in iframe

IsaacTakushi — Thu, 28 May 2020 18:48:49 GMT

Hi, @eduardoavargas.

Thanks for reaching out.

Off the top of my head, I don't know of a way for you to edit a HubSpot CRM card/extension's iframe attributes, but I want to pose your use case to my team.

Can you confirm your app ID? If you have a link to an example record which contains such an iframe action, that would be very helpful as well. Feel free to share these details with me via direct message.

Re: How to add the allow-downloads flag to the sandbox tag in iframe

eduardoavargas — Thu, 28 May 2020 19:43:11 GMT

Thanks for the feedback

My app Id: 196032

I will send print because we have sensitive data in the application

By clicking on this image (Captura3.png) the file is downloaded to the user's machine. everything was fine until the chrome update.

One more detail, this iframe is for users logged in. I use the authentication of the hub to authenticate myself in my application.

Re: How to add the allow-downloads flag to the sandbox tag in iframe

IsaacTakushi — Fri, 29 May 2020 14:09:04 GMT

Thank you for sharing this, @eduardoavargas.

One more point of clarification: What happens when a user attempts to download the files? Does Chrome throw an alert or only a warning or error in the console?

Re: How to add the allow-downloads flag to the sandbox tag in iframe

eduardoavargas — Fri, 29 May 2020 16:12:25 GMT

Good afternoon @IsaacTakushi

Yes, post a warning on the console.

Download is disallowed. The frame initiating or instantiating the download is sandboxed, but the flag ‘allow-downloads’ is not set. See https://www.chromestatus.com/feature/5706745674465280 for more details

Re: How to add the allow-downloads flag to the sandbox tag in iframe

IsaacTakushi — Thu, 04 Jun 2020 19:06:16 GMT

Thank you, @eduardoavargas.

I'll share this with my team to see what options we have available.

I appreciate your patience!

Re: How to add the allow-downloads flag to the sandbox tag in iframe

IsaacTakushi — Thu, 04 Jun 2020 19:07:30 GMT

Hey, @eduardoavargas.

I wanted to let you know that we're still discussing this internally. We haven't forgotten about you!

Thanks for your continued patience.

Re: How to add the allow-downloads flag to the sandbox tag in iframe

IsaacTakushi — Tue, 16 Jun 2020 12:51:55 GMT

Thanks for your patience, @eduardoavargas.

On Friday, June 12, 2020, the team added the allow-downloads flag to CRM card iframes. Download functionality should now be restored for customers on Chrome 83!

Re: How to add the allow-downloads flag to the sandbox tag in iframe

Kavya — Mon, 30 Nov 2020 13:27:25 GMT

Hey, I'm still getting the same error(Download is disallowed. The frame initiating or instantiating the download is sandboxed, but the flag ‘allow-downloads’ is not set) when I try to download the HTML document as PDF using HTML2canvas function.

Version of my Google chrome is (Version 87.0.4280.66 ).

Can anyone help me through this?

Re: How to add the allow-downloads flag to the sandbox tag in iframe

nbrown8 — Mon, 25 Aug 2025 17:30:39 GMT

@IsaacTakushi

Is there any update on enabling the same functionality within the CMS page editor ? There are a significant number of use cases where a user might want to be able to downloads there also

These ranges from interactions with widgets that allow drag-and-drop file uploads, downloads, and any other JavaScript package with similar function, to theme defined developer extensions, editing and also chrome and other extensions layering function.

Likewise for enabling "allow-modals" in both contexts and the private apps / cards lack the ability to pass full request parameters which meeans you can not pass abort controllers etc

Re: How to add the allow-downloads flag to the sandbox tag in iframe

Victor_Becerra — Mon, 25 Aug 2025 21:50:26 GMT

Hi @nbrown8
Thanks for your comment! To ensure your question or topic gets the best visibility and a wider range of responses from the community, it's usually best to start a new thread rather than adding to an older one.
A fresh post will help your query stand out to everyone who browses the forum, increasing the chances of someone with relevant insights or solutions seeing and responding to it quickly. Feel free to tag me in the post and I'm happy to get you started.
Best, Victor