From the message in the error box, it is possible your theme image storage is full and you need to delete some images which are no longer required. Thing to note, the theme storage size is fixed and cannot be increased.
Admin Home > Themes > Theme Manager > Theme Settings > Images tab and scroll down to Custom Theme Images.
Also make sure that the image you want to upload is less than 1MB in size.
Last Edit: Jan 10, 2021 23:29:37 GMT -8 by Nscalerr
My Forum - When the snows fall and the white winds blow, the lone wolf dies, but the pack survives. Eddard Stark