iPhoto to Photos
I cannot import my iPhotos Library after updating to a new iMac with Monterey
Where is the iPhoto Library stored? If it is o an external volume, check if this external volume is compatible with Photos: It should be prepared as described here: Move your Photos library to save space on your Mac - Apple Support
On macOS Monterey I would not try to import the iPhoto Library but to open the iPhoto Library in Photos to convert the iPhoto Library to a Photos Library. This will give the better results, as you can save the album and keywords.You can migrate the structure of the library and most of your work done in iPhoto, not just the original image files.
Try the following:
- Lauch Photos while holding down the options key ⌥ and wait until the dialog to select a library appears. Then release options key.
- Now select your iPhoto Library to open it in Photos hit return. Then wait for Photos to create a new library. It can take several hours, if your iPhoto Library is large.
Photos will create the new Photos Library on the same volume as the iPhoto Library. So this volume needs to be compatible with Photos.