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[Maineit]

Version: r1605
Server: Apache/2.4.41 (Ubuntu)
PHP version: 7.4.3-4ubuntu2.19

When attempting to upload files via Google Chrome or Microsoft Edge, the message "Your browser doesn't support HTML5, Flash or Silverlight. Please update your browser or install Adobe Flash or Silverlight to continue." is displayed.

If you click the "Upload Files" button, it loads a blank page.

[jackald]

I had this issue when under Options > General Options the System location - System URL value was set to http:// not https://

[Maineit]

I had this issue when under Options > General Options the System location - System URI value was set to http:// not https://

It is configured as https:// already.

[BlunoMoretti]

Any solutions so far?

[klejen]

I had this issue when the 'unsafe-inline' was not inside the Content-Security-Policy.

try to set this:
add_header Content-Security-Policy "default-src 'self' http: https: data: blob: 'unsafe-inline'" always;

[JayCroghan]

I had this issue when the 'unsafe-inline' was not inside the Content-Security-Policy.

try to set this: add_header Content-Security-Policy "default-src 'self' http: https: data: blob: 'unsafe-inline'" always;

This didn't work either :(