When doing a pre-migration check or copying a site object, the following message is displayed:

The term set this column refers to cannot be found in the source site.The column seems to be corrupted.

Error code

The message is displayed when the term set used by a source column is missing at the source.

Here is an example for a column named "Project" that is driven by a term set "Projects". Here is the term set:

In this example, the error indicates that the term Set Projects cannot be found in the source.

When this occurs, it indicates that the source column is corrupted and no longer contains any valid data. As a result, the column can often be deleted without losing any critical data.

Another way to resolve the issue would be to update the column's settings to refer to an existing term set. This can be done by going to List Settings, clicking on the column, and then selecting a term set in the Term Set Settings section.