I'm opening an Excel file and when I try to insert a new row or column I get a message error giving me a large text about how this is not possible. I have seen many people facing this message, although this gives the solution, sometimes it's hard to understand what this message is trying to say.
But, what's happening? Let me tell you that you' re using all the rows or columns of the file, yes, believe it or not you are having information (even blank space) at least at the last row or column allowed. So, when you want to add a new one, Excel tries to delete this row or column because it will be out of range with the new element inserted.
The solution is going to the last column or row, to do so you can use this shortcut: Ctrl + Down arrow if you want to go to the last row or Ctrl + Right arrow to go to the last column, as shown in the images.
Then, you just have to select the entire row or column and delete, the next step is to save the file to to let Excel to detect this change, once you did this you'll be able to add one row or column, if you need more just follow the same procedure but deleting more rows or columns.