Upgrade from iPhoto to Photos in Yosemite

[rnckw]

For many years I have imported photo's to iPhoto running on a MacBook Pro, from a variety of sources for example: Old Mac,different cameras,DVD's,CD's,Carbon Copy Backup and have inadvertently created several different library's whilst doing so.
Now I am trying to upgrade to Photos in Yosemite and although I have managed to copy most of my pics to a separate USB drive I am getting the following problem messages:
Unrecognised Data
Unable to import due to lack of Metadata and so on. At this moment in time my NEW photo library is approx. short of 25,000 photo's.
Can some kind person suggest a work around to help me sort out this mess.

 

[TattooedMac]

How many images are we talking, that give you this error ??
What are you using to import them into Photos (meaning, are they already on your Mac or are you trying to import straight from a USB/DVD/CD and so on)?

Have you tried to import them into iPhoto first to see if they 'take' in that App first ? If they are on a USB/DVD/CD etc, have you tried importing them using the Macs Image Capture App, found in the Utilities Folder in Applications ??

Basically, I don't know here these images are at the moment, so I can't really give any advice in how to import them into Photos.

Images that usually give this error, mean, you only have the Thumbnail version of the image, and not the whole complete image. Its like having them in iPhoto, and you get the grey screen with the ⃠ where the image should be.

 

[rnckw]

Firstly many thanks for taking the time and trouble to offer help with my problem, it is much appreciated.
My total iPhoto program contains about 20 GB's of pics but as I have created several different libraries I now realise that many are duplicates and as you suggest possibly Thumbnail images.
After copying the first Library to a separate USB drive, I continued trying to copy the rest to the same drive but on each occasion received the message that there were duplicates and I could either cancel or replace the image. In some instances as many as several thousand in total. I clicked on replace.
So I now have a USB drive with supposably all my photo's which is obviously useless and to clean up the system before upgrading I deleted all the iPhoto app files etc.
I am not familiar with the "Image Capture App" that you mention but will now go back to square one - I have a cloned copy of my system which I can re-install (Carbon Copy Cloner) and start again.
Any advise that you can give for the transition would be of great help.
With kind regards and many thanks.