We have seen inconsistent results in uploading media to Canvas through the rich text editor. Click the images below to enlarge the view.
Depending on your browser or its configuration you may receive an error message when using the Upload Media tab.
Here is an alternative method for uploading your file. It requires that you have permissions to use the file tab. Only instructors have permission in a course but students also have permission in Canvas groups.
The first step is to go to the files manager using the file tab in the course or group.
This will display the file screen where you can upload files. Click Add Files and select the file to upload.
After you upload the file then you can go to any content item (page, discussion, assignment, etc.) and use the rich text editor to link to your file from within the content item.