The size of discuz Forum attachments is limited to 2 MB.

The size of the discuz Forum attachment that is initially installed is limited to 2 MB by default.

First, you need to modify the PHP parameter configured for the server space to allow the size of attachments to be uploaded. PHP. INI is stored in the C drive windows or system32 directory:
Post_max_size = 8 m (the maximum limit for form submission. This option is not to limit the size of a single file to be uploaded, but to limit the whole form data submitted)
Upload_max_filesize = 2 m (maximum size of a single file to be uploaded)
Make sure post_max_size> = upload_max_filesize, that is, the former is not smaller than the latter.
After modification, you must restart the web service.
Note: If the modification does not take effect after the Web is restarted, it may be your modified PHP. the INI file is not the file used by PHP of course. Make sure that you modify the PHP file currently in use by PHP. INI file.

Next, modify the size of the uploaded attachments in the "user management"> "User Group details" section on the background of the Forum.

The modification of the uploaded attachment must be confirmed successfully.