I know that one.

Some of your lines has one more column than the rest.

It can be some error in the extraction, or in the local modification when creating the civ

There is other possible reason for that: you have a separator INSIDE the values of a column.

So imagine you have a .CSV, with ";" as separator. So far so good, Celonis will tell you ok.

But imagine that in one record, you have some textual description like "John Doe, Ph.D"

Well, I found that Celonis, even as I told it the separator will be ";" it still will parse the "," in the textual field.

So it will end up with one column more that the other lines:

"John Doe, Ph.D" will become in Celonis as 2 columns: "John Doe" AND "Ph.D"

HTH