File cannot be opened for reading

Trying to "text file to tag" for an album title but get message file "cannot be opened for reading". How do I resolve this? I was able to add the track number using Tools and I can change the album titles individually but not doing it as a batch.

The error message should show which file cannot be opened for reading.
This could be the text source file or the target file.
Which one is it?
(Although it looks more like the source text file.)

It has to be a plain text file, not one created by an editor that adds metadata like the office editors.