I have checked your web.config and it’s correct - I was able successfully run the Viewer and render your tif file.
If after library update you have same issue - please share with me Viewer widget and beck end code that you use.
Also please clean/rebuild your solution and clear it’s cache. Could be that you still use the old version. To ensure which version your solution use when it’s run you can use such code:
Somewhere on the web page and you will see such info
, if your solution runs with the latest version of the Viewer you will get same version as on the screenshot.