Error 403 while uploading photo

[diegogurr]

After 1 week of posting photos (every 4 hours,using crontab) without problems now it says 'Photo Upload failed with the following response : <Response [403]>
My code for publishing:

def publishPost(path,description):
    try:
        cl.photo_upload(path,description)
    except LoginRequired:
        cl.relogin()
        cl.dump_settings(s_path)

What could be the problem?How can I solve this?