The ringtone format is incorrect. The ringtone format needs to be converted to m4r format first.

The specific process is as follows:

Open itunes - click File - Add file to library - Select the song you want to make a ringtone in the pop-up dialog box, click Open - —Right-click on the song and select Show Introduction — Click Options to adjust the start and end time you need, about 40 seconds, click OK — Then right-click on the original song to create an AAC version — a duration of 39 will appear Seconds clip, right-click on it - show it in Windows Explorer - the explorer is a music in m4a format, change the file name suffix to m4r format - click and hold the ringtone in m4r format and pull it to itunes ringtone , added successfully