There are a few reasons why you might see an Application Error when you attempt to upload a new Event Banner, through the Event Information section. These include:
Check the file size of the image. Maximum allowable file size when uploading the Event Banner is 500kb. To reduce file size of an image, most programs have a 'Save for Web' option that will reduce the file size of an image without compromising the quality.
The size of an image usually goes hand in hand with the file size of an image. Generally photos taken directly from a camera, or created for print, are large in both file size and image size. Check the image dimensions of the image first (through image properties), and try to resize it to the minimum size required to fit the event. For example, a photo taken direct from a camera could be over 3000px wide. Common banner sizes on our event templates are:
Old templates - w: 985px by h: 204px
Mobile optimised templates - w:1170px by h: 400px