My mesh is weird when I uploaded

[PeoniesGarden]

So, I rigged my mesh, but I don't know what happened. Everything was good until I uploaded it. The clothes look nice when I finish, but as soon as I upload to SL, it's getting a weird thing.

The sleeves of the shirt are zigzagging at the back. I really don't know what to do anymore. The rest is fine!

[Quarrel Kukulcan]

What direction are your armature and your mesh facing, and have you applied rotation & scaling to both?

[PeoniesGarden]

So I applied the rotation and scale, but I didn't rig in T-pose, so that was wrong 😅 I fixed it and made my first ever (good) clothing item 🥰 I'm so happy! Even though it's for an outdated body, it's perfect

Thank you all for the help!