Export page as PDF get blocked by chrome Mixed Content policy

[Luis Ashurei]

Hi,

Our confluence version is 7.15.0, user click "Export to PDF" in chrome will not download the pdf, but can find a chrome console warning:

Mixed Content: The site at 'https://xxx/' was loaded over a secure connection, but the file at 'https://xxx/download/temp/pdfexport-20220819-190822-0833-11869/29532022_551de2aad63a46cfa69313439e71a734-190822-0833-11870.pdf?contentType=application/pdf' was redirected through an insecure connection. This file should be served over HTTPS. This download has been blocked. See https://blog.chromium.org/2020/02/protecting-users-from-insecure.html for more details.

I trace the download link, steps are:

1. hit "https://xxx/spaces/flyingpdf/pdfpageexport.action?pageId=29532022"

get a 302 response to "http://xxx/download/temp/pdfexport-20220819-190822-0838-11873/29532022_bf622f18bd7e4985ac06efcc90bb16ab-190822-0838-11874.pdf?contentType=application/pdf"

(note that is a http, not https response)

2. chrome auto try "http://xxx/download/temp/pdfexport-20220819-190822-0838-11873/29532022_bf622f18bd7e4985ac06efcc90bb16ab-190822-0838-11874.pdf?contentType=application/pdf", then get 302 to https one "https://xxx/download/temp/pdfexport-20220819-190822-0833-11869/29532022_551de2aad63a46cfa69313439e71a734-190822-0833-11870.pdf?contentType=application/pdf"

3.  another auto redirect to the https link "https://xxx/download/temp/pdfexport-20220819-190822-0833-11869/29532022_551de2aad63a46cfa69313439e71a734-190822-0833-11870.pdf?contentType=application/pdf", but the file was blocked, warning above displayed in console

"Mixed Content: The site at 'https://xxx/' was loaded over a secure connection, but the file at 'https://xxx/download/temp/pdfexport-20220819-190822-0833-11869/29532022_551de2aad63a46cfa69313439e71a734-190822-0833-11870.pdf?contentType=application/pdf' was redirected through an insecure connection. This file should be served over HTTPS. This download has been blocked. See https://blog.chromium.org/2020/02/protecting-users-from-insecure.html for more details."

Not sure if it's relate to this chrome issue (ref), bug, maybe?

But is there any workaround like set the "flyingpdf/pdfpageexport.action" response to https rather than http?