Unable to change existing column type from Text to Multiline Text

[CTFlorian]

I have never seen this before.  when I change the field type to multiline text I get:

Non-supported field type change.

This is when using Classic. In modern I get the same thing.  In PowerShell I get the same thing.

What's going on?

[#2]

@CTFlorian I can change single line of text column to multiple lines of text column without any problem: 

Can you show us the screenshot of error? Can you try same in another list on same site?

---

Please click Mark as Best Response & Like if my post helped you to solve your issue. This will help others to find the correct solution easily. It also closes the item. If the post was useful in other ways, please consider giving it Like.