Is this the wallet you'd sent that TX last year from? If it ever worked (on this computer) then you must have that folder somewhere, it's where your private keys and the blocks are stored. Note that I'm not saying the Library folder in the root level of your hard drive, but the one in your User folder, which MacOSX now hides by default. To get directly to it, pull down the Go menu and select Go to Folder... and then paste this in: ~/Library/Application Support/Florincoin
Thanks guys!
Found the folder and made the change you suggested Blocktechceo. The error message is now gone but the app fails to open at the "loading block index" part of the process.
I tried loading a new wallet (Florincoin Core version v0.10.4.0-824d84f (64-bit)) on a mac that never had the florincoin wallet. I made a backup and copy of the wallet on the old mac that is giving me trouble and loaded the data from the old wallet into the new wallet. It seems like the new wallet updated the block index successfully. The only transaction still in limbo is the one I am trying to get back. BTW- The address that this transaction was sent to is my address so I can see that it was never received by that address.
Here is the transaction details as described in the new wallet (on the new mac).
Status: conflicted
Date: 6/21/16 20:34
To: F9gCji1FEyaq8rEv8F9N5dfT2ApzF8pfo9
Debit: -50 000.00000000 FLO
Net amount: -50 000.00000000 FLO
Transaction ID: 924be492c2837384fd0d2eee4af0ebe506f4c5a6962c5307dfaee41b7620474e-000
It looks like the transaction never got mined/confirmed in the mainchain, so those 50,000 FLO should still be in the wallet that had them before that transaction. You can confirm this by checking both the TXID and the recipient address in a block explorer, or a few if you want to be really sure.