Error: "Can't convert to number", but the collumn type is text

[Cartans1925]

I have a collumn that was previously type number (and the data in it was all numbers, obviously). Now I changed the content to text, aswell as the collumn type, but the error message shows

[Cartans1925]

I had a collumn with all numbers and number data type. Now I changed the collumn to be all text aswell as text data type. But there's an error message saying the text can't be converted to number, in despite of my change in the data type