Error: Multipart: Boundary not found

I got this when uploading files to my nodejs API from my react and react-native apps and the problem was with my axios version. i was running the latest at the time which is 0.25.0 so i had to downgrade to 0.21.4.
first uninstall axios

npm uninstall axios

then install version 0.21.4 or any other version that you have used before that works without getting this error. in my case it was version 0.21.4

npm install axios@0.21.4

Hope it works for you