Ensure that the file you're uploading is less than 500 megabytes; there is a hard limit of 500 MB for any file uploaded to Finalsite.
Make sure the file name does not contain non-alphanumeric characters such as #, %, @, < , /, *, &, [, ], ~, blank spaces, commas, apostrophes, or periods (other than the one preceding the file extension such as .pdf, etc). Such characters can sometimes throw off the scripts that detect the size of the file. Underscores ( _ ) and dashes ( - ) should not present a problem.
Note: We have implemented a function that replaces known problem symbols with underscores ( _ ) at upload. It is still a safer practice though to avoid all symbols other than _ or - in filenames, as there are many email clients that will "break" links to files if symbols are present in the filename, especially in an eNotice or other email.
Check the file size cap of the folder you are uploading to. Navigate to the folder in File Manager and click the "settings" link in the upper-right corner. There you will see if the folder has a size limit. Verify that the amount of space remaining is enough to accommodate the file(s) you are attempting to upload. You can increase the limit if necessary.