Are all these errors "safe"?

[glenbodie]

I dumped some metadata from a directory tree full of images, and I had -m in the command line. There were still some errors:
Warning: Bad NikonScanIFD SubDirectory start - File1.JPG
Warning: Invalid EXIF text encoding for UserComment - File2.jpg
Warning: Bad NikonScanIFD directory - File3.JPG
Warning: Bad PreviewIFD directory - File4.jpg
Most of there were repeated many times. The NikonScanIFD is particularly odd since I am certain none of those files were ever "scanned" and my only scanner is a Canon - they came straight off the camera and were adjusted with image editing software. Many other files followed that same path and had no errors.

I recognize the most if not all of these errors will get corrected when I write some updated metadata, so that's nice. Is there anything else I should do to clean these up?

[Phil Harvey]

The bad IFD's are common if you used other software to edit the files.  The invalid EXIF text encoding is indicative of crappy software too.  The problems only affect the NikonScanIFD which contains no useful information, and possible loss/corruption of the PreviewImage and UserComment.  None of the other metadata should be affected.

- Phil