The standard limit for files that are imported to Palette is around 8MB. The limit applies to alla types of files that are attached; i.e. contracts, invoice images, and files attached to a comment.
If this is a recurring problem for you, and you need to be able to attach bigger files, it is possible to increase the limit in the web config file. Register a ticket if you want more information on how to do this. If the limit is increased, it can affect the performance in Palette, and invoices can take longer to load. It also takes up more space on the server.
If this is not a recurring problem, we recommend that big files are split into smaller files, so that they can be imported.