Help with "The Finder can't complete the operation because some data in "iPhoto Library" can't be read or written. (Error code -36)" Any ideas on how to fix this?

Question

While trying to copy my iPhoto Library (49.61 GB) to an external hard drive, I receive the error message "The Finder can’t complete the operation because some data in “iPhoto Library” can’t be read or written. (Error code -36)"
I need to move my library because I have no more disk space.  This was going to be step 1 followed by backing up to another EHD.
More details: iPhoto version 9.6 (910.29) OX X Yosemite Version 10.10.1 (Mid 2011 Mac Book Air).  EHD= WD Elements 1 TB (purchased at B&H Photo where the sales associate formatted it for a Mac).
Any step by step ideas for help are appreciated!  I've read through a few threads but need more step by step directions.

Answer 1

That error message is an I/O error which can mean a number of things, among them a bad file.  Here's a couple of fixes you can try:
1 - use the free version of  iPhoto Library Manager  to rebuild the library with the rebuild being created on the  EHD as follows:
Using iPhoto Library Manager  to Rebuild Your iPhoto Library
1 - download iPhoto Library Manager and launch.>Click on the Add Library button,
2 -  select the library you want to add from those in the selection window.
3 - make sure that in the rebuild window the checkbox  "Scavange orphaned photos" is checked.
4 - now that the library is listed in the left hand pane of iPLM, click on your library and go to the Library ➙ Rebuild Library menu option
5 - in the next  window name the new library and select the location you want it to be placed. Click on the Create button.
Note 1: This creates a new library based on the LIbraryData.xml file in the library and will recover Events, Albums, keywords, titles and comments. However, books, calendars, cards and slideshows will be lost.
Note 2:  Your current library will be left untouched for further attempts at a fix if so desired.
When iPLM finishes it will display a log file entry showing which files it was unable to use in the rebuild.  Open the old library with iPhoto, locate and delete the photos that iPLM listed in its log.  Then try dragging the library to the EHD again.
If the above fails continue with:
2 - create a new, empty library on the EHD.  Use the paid version of iPhoto Library Manage to copy the events (1-2 at a time) to the new library on the EHD.  At one point iPLM may run into the bad file and be unable to copy the event.  You can check iPLM's log to see what file it is.  Then open that library, delete the file and either try to copy the entire library by dragging and dropping or contine with the copying of events from the old library to the new library.