Unable To Write To Iphoto Library

Unable to write to library iphoto library

Opened iPhoto library with Photos and it migrated the pics to Photos library, used it for a week, then opened a different library on an external drive which Photos migrated. Now when I try to switch to the original library, Photos will not recognize the library even though Finder shows it as migrated. Where iPhoto Pictures Are Stored. IPhoto pictures are stored within the home /Pictures/ directory, in a file called iPhoto Library. But with newer versions of iPhoto, iPhoto Library became a package file rather than a folder, so in order to access the original picture files you have to go one step further in one of two locations.

Unable To Write To Iphoto Library

Unable To Write To Iphoto Library

I am having trouble moving my photo library file to my Seagate external drive.
I am using OS X el Capitan 10.11.1 & my Seagate drive works perfectly well with the Mac (it is OS X Extended (Journaled) format), I can read/write to it as usual.
When in Photos, I am in Preferences (General tab) and am trying to change the library location of the .photolibrary as described by Apple.
When I move the file to the external drive and then double click, I get the message .....
Switch Libraries - do you want to switch the current Photos Library to from 'old library' to 'new library'
I then click on 'Switch', after a few seconds I get the message....
LIBARY COULD NOT BE OPENED. PHOTOS HAS ATTEMPTED TO REPAIR THE LIBRARY 'NEW LIBRARY' BUT IS UNABLE TO OPEN IT
when I look at Console I get the following error:
Mar 9 18:53:25 Richards-MacBook-Pro PhotosRelauncher[7520]: App to relaunch:file:///Applications/Photos.app/, library:file:///Volumes/4TB%20External%20Drive/Photos%20Library%20NEW.photoslibrary/
Mar 9 18:53:25 Richards-MacBook-Pro PhotosRelauncher[7520]: Launch with library url.
Mar 9 18:53:26 Richards-MacBook-Pro com.apple.xpc.launchd[1] (com.apple.xpc.launchd.domain.pid.Photos.7521): Path not allowed in target domain: type = pid, path = /Library/Frameworks/iTunesLibrary.framework/Versions/A/XPCServices/com.apple.iTunesLibraryService.xpc error = 147: The specified service did not ship in the requestor's bundle, origin = /Applications/Photos.app
Mar 9 18:53:37 Richards-MacBook-Pro Photos[7521]: Error: Error Domain=com.apple.reddwarf Code=26 'RDErrorLibraryOnUnsupportedFilesystem' UserInfo={NSURL=file:///Volumes/4TB%20External%20Drive/Photos%20Library%20NEW.photoslibrary/, NSLocalizedDescription=RDErrorLibraryOnUnsupportedFilesystem, NSUnderlyingError=0x7f9ded461c70 {Error Domain=com.apple.lithium Code=321 'LiErrorUnsupportedFilesystem' UserInfo={NSURL=file:///Volumes/4TB%20External%20Drive/Photos%20Library%20NEW.photoslibrary/, NSLocalizedFailureReason=Windows NT Filesystem, NSLocalizedDescription=LiErrorUnsupportedFilesystem}}} while trying to open Photos Library NEW.photoslibrary
I have tried rebuilding the drive with disk utility, same result - I also have a second Seagate drive I use elsewhere, tried it on that, same result.
I have spoken to Seagate, they say their drive should work, it is a mac issue... anybody any help on this issue please?

Unable To Write To Library Iphoto Library