SINOPEC Bidding System uploading files is stuck at 30% because of network delay, which can be solved by re-uploading or replacing the network cable.
If the network is unstable, you can refresh the web page or restart the network equipment to re-upload.
If the bid file is too large, you can compress the file into a number of small zip and unify the name, and then upload a document stating that the file is compressed into a number of small zip.