If you are still looking for a more robust solution you can try PlumePack plugin, there is now a FREE version for the equivalent of "Collect & Copy" feature of the Project Manager.

Here it is August 2021 and I go to copy a project using project manager and I get an error message and then after waiting for the project to transfer to the new location as soon as I click the error message the project disappears. I am so sick of the bugs in adobe that are not getting fixed but I am definitely going to move my projects to a different software as soon as possible. This is the most buggy editing software I've ever used.

You can try to collect & copy on the same hard drive your project is, and then copy, paste the generated project and dependencies to your new hard drive. It will perhaps solved this issue.
And if your new hard drive is a network hard drive this could also explained why it didn't work. Not sure Project Manager works fine on network hard drive...

There is a non free alternative called PlumePack, that solves some Project Manager bugs and allows you
to trim losslessly your files: https://www.autokroma.com/PlumePack.
Best,
Marion from Autokroma

The project manager is NOT fit for purpose. It's probably the worst thing about this software. Nice they doing teams and sharing but I think Adobe really needs to sort this aspect of Premiere out.

If it wasn't for After Effects I would've have ditched this software years ago.

July 2020: Project manager will not copy project that is only 2.1TBs large. Tried unchecking every box on export. Tried going thru log notes and descriptions and removing any dashes, comma's apostrophes, periods etc. All file names are clip names natively so there was nothing to change.

I fails when I try one timeline or a dozen at a time. What the ****?

I've tried everything from importing the sequence into a new project, creating xml and opening up in older versions of PP, and all sorts of workarounds, and project manage is STILL not working - Unknown Error occurs.

Adobe, PLEASE FIX THIS. Project Manage is such a crucial workflow in delivering to colorists for me. PLEASE take a look at this issue!

Here we are almost in March of 2020 and the same issue is arising for me. Are there any fixes you gentlemen were able to find?

The Project Manager seems to be working when I uncheck "Exclude Unused Clips" But in my particular situation, this is going to be quite a bit of files that I don't need.

I wonder, Kevin, if importing the sequence into a new project is something that worked for you? Other solves I've seen is to ensure that there are no files with special characters in their names... For me, these sequences do not have that and it is still showing an error.

This is very frustrating. I wish Premiere would show where the error is occurring from.

Try importing the sequence into a new project.

I have the same problem. Please fix! This is an essential feature. It needs to work!

Project manager hangs for me in 2019 when it goes to 'analyze project'. I downgraded the project to 2018 and it works fine.

Having the same problem when 'Exclude Unused Clips' is selected