What is JotForm?
JotForm is a free online form builder which helps you create online forms without writing a single line of code. No sign-up required.
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We believe that if one user has a question, there could be more users who may have the same question. This is why many of our support forum threads are public and available to be searched and viewed. If you’d like help immediately, feel free to search for a similar question, or submit your question or concern.
Upon checking your form's upload question, I found that powerpoint extensions "ppt and pptx" are already in allowed list of file extensions. Please check the screenshot below:
You should not have any trouble in uploading the files with ppt and pptx extensions. I just tried to upload a ppt file in your form and I was able to do so, it did not show any error message.
Please share the file extension which you are trying to upload and we will take a look.