I'm able to download a pdf from yahoo mail. see screenshot What do you have set in the security settings? see 2nd screenshot

Have you tried Firefox in Safe Mode? https://support.mozilla.org/en-US/kb/diagnose-firefox-issues-using-troubleshoot-mode#search Did you clear the browser cache? https://support.mozilla.org/en-US/kb/clear-cookies-and-site-data-firefox

Hello Jon, I don't recognize the way you showed me in your screenshot when you are downloading a file from the yahoo mail. So, when I am downloading a pdf file from my yahoo mail or yahoo small business mail I am just pressing on the right down corner of the image of the pdf file and then Firefox opens a new Window in which the pdf file is displayed (in the Applications of Firefox I set for downloading pdf files - Open in Firefox - which is the default). Then I press download and I can download the pdf in my device.

On the other hand, today when I installed last Firefox Version 101.0, I am getting the following problem which I described: "Problem loading page" Firefox Can’t Open This Page To protect your security, dl-mail.ymail.com will not allow Firefox to display the page if another site has embedded it. To see this page, you need to open it in a new window. Learn more… Open Site in New Window

This means that in order to open the pdf file I have to go to a new Window. May be this is a bug of the last 101.1 version of Firefox.

Yes, I deleted cache and cookies and today history, but nothing changed. Also I disabled Add-ons like the Safe mode, but didn't change anything. In the security settings I have the same like you, which is the default by Firefox (in general I do not change the default settings set by Firefox) I asked also Yahoo support and they answered that this might be a Firefox issue of the last 101.0 Version, as all other browsers are working excellent.

I would stop using http://dl-mail.ymail.com/ and just use mail.yahoo.com or yahoo.com. It appears that the dl is for downloading which is what I see when the download windows comes up. see screenshot So there is no issue.

Hello Jon, I am not using http://dl-mail.ymail.com/ either, I am only using mail.yahoo.com for my yahoo mail. The dl-mail.ymail.com I saw for first time, when appeared in the error message by Firefox, I already described "Problem loading page". Besides, when I am clicking on the dl-mail.ymail.com then this brings me to the following Yahoo page:

yahoo ! Will be right back........ Thank you for your patience. Our engineers are working quickly to resolve the issue.

What do you understand by the above message of yahoo ?

If you click on the dl-mail.ymail.com what can you see ? You see the same message as me ?

On the other hand, the way you are downloading pdf files from your yahoo mail according to your screenshot is much different than my way I already described. Why this difference ?

Gotcha. I get the same message when clicking on dl-mail.ymail.com. I see that you can open the attachment without opening the email. This will open the pdf and then I can view it and then download it. In my screenshot I open the email first and then just downloaded the attachment. If there is something different please show it.

Hello Jon, No of course there is no possibility to open the attachment without opening the email. So the procedure is the following: First I am opening the email. Then I am clicking on the down right corner of the image of the attachment. Firefox opens then the attachment (pdf) in a new Tab of Firefox (in the pdf viewer of Firefox). If I want then to download the attachment in my PC I have to click "download" in the new Tab of Firefox. So, the procedure to download an attachment in my computer is two steps and not one like yours.

On the other hand, yesterday immediately after downloading the 101.0 update of Firefox, then the procedure became three steps. So, before opening the pdf in the new Tab of Firefox, I am getting the error message "Problem loading page", etc, etc, etc. and I have to click on "Open Site in New Window".

So, is this an issue by Firefox or by Yahoo ?

Yahoo support assured me that this is an issue of the last update 101.0 of Firefox, as all other browsers are working excellent with the downloads by Yahoo and so this issue should be fixed by Firefox.

I have the same problem except it is from AOL.

To protect your security, dl-mail.aolmail.com will not allow Firefox to display the page if another site has embedded it. To see this page, you need to open it in a new window.

Is this firefox related?

This is the error message I get with AOL:

To protect your security, dl-mail.aolmail.com will not allow Firefox to display the page if another site has embedded it. To see this page, you need to open it in a new window.

Report errors like this to help Mozilla identify and block malicious sites

Screenshot of the firefox bug here. I get the same problem except its on AOL mail server. This just started happening today for me.

Prox,

Welcome to the party. Can you both try a different version of Firefox to test? https://www.mozilla.org/en-US/firefox/all/#product-desktop-nightly

Again, this is just a test.

Hello Prox, Yes you have exactly the same error message like me. This started with the last update 101.0 of Firefox. So, the moderators of Firefox please to find ways to fix it, in next updates. Hello Jon, Firefox is only one. There are only different languages. I have the US version.

Hey All, I assume the "Open Site in New Window" button works with that embedded content, so while this is annoying, you still can get the document?

Background

Sites can set rules for whether to allow embedding their pages/documents in other sites. I'm not aware of any change in how Firefox 101 interprets those rules compared with Firefox 100, but it sounds like something is being read a bit more strictly, or Firefox is mistaken in thinking it is a cross-site embed.

PDFs, Firefox's built-in viewer, and forced downloading

Is the problem specific to PDFs or are other kinds of attachments affected?

Firefox 101 made a change in PDF handling for this situation:

• On the Settings page, Portable Document Format (PDF) is set to "Open in Firefox"
• The site sends a forced download header (Content-Disposition: attachment) to try to bypass the built-in viewer

In Firefox 98+, Firefox ignores the attempt at bypassing the view. In Firefox 98-100, the PDF often opened in the same tab, replacing the content. Much grumbling ensued. Starting in Firefox 101, the PDF opens in a new tab instead. I don't know whether this is relevant to the problem.

As a test, you could turn off automatically using the built-in PDF viewer -- for example, change temporarily from "Open in Firefox" to "Always ask". This article has the steps: View PDF files using Firefox’s built-in viewer. Does that make any difference?

Screenshot questions

Is this a restricted pop-up window, with most of the normal toolbar area missing, or a regular window:

It's puzzling that it has a "i" icon next to the address instead of the lock icon. That doesn't really make sense.