So I upgraded to MacOS Sierra and now whenever I try to do anything in my working copy I get the error that it
"is too old (format 29) to work with client version '1.9.4 (r1740329)' (expects format 31). You need to upgrade the working copy first."
When I run svn upgrade, as it suggests it says "Can't open file /.svn/entries: No such file or directory"
Any suggestions will be greatly appreciated!
Your problem is that the version of the SVN client got upgraded locally; whereas your local working copy (and the server) didn't change! Now the new client is unable to work with the existing working copy.
Now you have three choices:
For option 1, you might look here or there.
For option 2, this might help.
Option 3; I guess, is the one-line-no-brainer which maybe costs you download time, but should come with the least amount of "you spending your time" debugging this (unless you got a ton of uncommitted changes sitting in your current repositories). But of course, you would first try to create a new checkout with the new client, before throwing the old directory away.