Hi – I had exactly this problem and searched forums etc, - was very frustrating as a newly paid subscriber and wondered why I upgraded. However I just contacted support and got a quick reply that worked straight away and was so simple - I had to be in the chatgpt 4.0 model to upload - worked straight away! . Pity that ChatGPT could not diagnose itself! Mind you with all the false promises it has made me thus far about deliverables I am not surprised. From Support: 1. File Uploads (“Add files is unavailable” / button greyed out):
- Make sure you’re using the GPT-4o or GPT-4 model in ChatGPT, as file uploads (including images and documents) are only available when you have one of these selected. If you are using a model such as “o1” or “o1-mini,” the upload feature is not supported—even on Plus.
- On both desktop and mobile, you should see a “+” or paperclip icon next to the chat input when file upload is available. If this remains greyed out despite selecting GPT-4 or GPT-4o, you may be hitting a different technical issue..