Error 36 is an input/output error. It can be caused by several things, such as:
- Corruption in one or more iMovie projects in the iMovie library, or corruption of the library itself;
- Improper format of the destination drive or originating drive;
- Unstable connection between the external drive and the Mac;
- Restrictive permissions that are prohibiting the transfer;
If No. 1 is the issue, you can try creating a new library on the destination drive and transferring each project individually from your originating library to the new library. In the process you might discover a corrupt project that is causing the issue. If so, expand your timeline in the project and slowly scroll through looking for white flashes, black frames, artifacts and any other signs of corruption, and cut out any that you see.
If No. 2 might be the issue, do a control-click/get Info on each drive and make sure that each drive is formatted Mac OS Extended (Journaled). If they are not that format, that might be the cause of the problem. In such case you can reformat the appropriate drive to Mac OS Extended (Journaled) using the disk utility app on your Mac. Be aware that reformatting erases all data on the drive, so be sure first to back up each drive before reformatting.
If No. 3 might be the problem, check all of your wires and connections, and sockets, that you are using to make sure that they are functioning correctly. Replace any connections that are defective.
If No. 4 might be the problem, do a control-click/get info on each drive and on the library and make sure that your permissions are set to Read/Write and are not limited in any way. On the drives, check the box at the bottom of the Get Info box, that says "ignore ownership on this volume".
-- Rich