Knowledge Base
Instructure Canvas - White screen (or crash) occurs when logging in to Canvas

When a student logs in to Canvas they are taken directly to the "Dashboard" where all their courses are listed. If the student experiences a crash of LockDown Browser (or a white screen) at this point, it's possible that your Canvas instance has a new feature enabled called "Enable Dashboard Images for Courses." This feature permits faculty to upload photo images for the course card. These course cards are what are displayed to the student on the Canvas Dashboard, immediately after logging in.

course card image

If the images that were uploaded are too large, they can potentially cause LockDown Browser to crash or display a white screen. These large files also increase server load and bandwidth, regardless of whether LockDown Browser or a standard browser is in use. This can result in sluggish server behavior. 

Faculty must be sure to upload only small photos, because LockDown Browser does not cache images (like a standard browser would). Images should be decreased in size to roughly 40-100kb before uploading. At present, the upload process to Canvas does not automatically resize the photos for you. Faculty can upload smaller images by navigating to the course, then choosing "Settings" in the menu, followed by selecting the tab titled "course details" and selecting the "Choose Image" button.

Canvas provides instructions on the appropriate size for the images here:https://community.canvaslms.com/docs/DOC-10097

"For best practice, images should be approximately 262 pixels wide by 146 pixels high"

To check on the size of the photos that are currently uploaded to the course card, you can "right click" with your mouse on the image, then choose "view image info" (wording may vary, depending on the browser being used.)

Another workaround is to have student use a standard browser, log in to Canvas, and then hide courses that are utilizing the course card image feature from their Canvas Dashboard.

Alternatively, you can disable the feature altogether in Canvas to immediately solve the problem. In Canvas, go to "Admin" > Choose your Account name > "Settings" > "Feature Options" and look for the header called "Course". Under that header is the feature titled "Enable Dashboard Images for Courses."