It seems very likely that the issue you're seeing is because something about the new content you are sending is problematic. The best way for us to help you troubleshoot this issue is to send us an email to email@example.com with the changes that you're trying to make when you update the campaign. We will be able to review this and give you some advice on how you can avoid the invalid content error moving forward.
How can i upload pdf file in constant contact using uploadFile method? Using following method image files are uploding successfully but when i am trying to upload Pdf files, an error "File extension Incorrect " is comming with status failed. As i know Pdf files needs to be uploaded inside Document library, is there any specific folder Id for adding pdf file inside Document folder?
The folder ID should not matter for what you are trying to accomplish. It is worth noting that the PHP SDK checks the specified file's mime-type to determine the extension and passes that on to the API. I would suggest double-checking the filename and checking the file itself. If you are still getting an error, it would be a great help if you can provide the exact error message.