What Windows OS and security software do you use? Please bear in mind that you can upload *.jpg files only.
I'm using Win 10 and this is what shows up when I try to use the trainer. It works just fine yesterday
I cannot see your uploaded file as it uses Chinese letters. Please either try again or upload your screenshot to, ie imgur and post the link here and tell us what security software you use.
I hope the upload can work this time
... no, nothing attached or uploaded. Just upload it somewhere and post the link here. And, please, what security software do you use?
Just windows defender and the firewall, nothing else, and for some reason, the trainer works again. I'm wondering if it is the Steam's problem.