Importing Data from folder with PDFs - Missing Page 4 on one of the files causing error

It looks like you may be combining files from a folder, using a custom function.  My response below is based on that assumption.  If that is not the case please let me know and I will revise.  On the query that combines all of the files you should see a step named something like #"Invoke Custom Function".  If you click this step and scroll all the way to the right you should see the column that contains all of the results from your transformation function.  In this column, you should also see errors, should they exist.  You can click on the column and then on the ribbon Home > Reduce Rows > Remove Errors.  This will remove all of the rows, or file per se, that have errors. It is advisable, however, to have a version without errors as just described, and then an error log, so you can debug should you wish to do so.