To upgrade to Mac OS 10.15 (Catalina), I had to upgrade my old Scansnap s1500 to an ix1500 and Devonthink 2 to Devonthink 3, even though the old scanner and software were working just fine in 10.14 (an unexpected $500 expense – thanks Apple).
The Devonthink help article for configuring Scansnap Home is out-of-date and incomplete, as are the various threads I found here. Here are the steps I took – perhaps others will find this useful. Please add any corrections or enhancements.
1 - Start Scansnap Home and go to Scansnap Home > Preferences > Application.
2 - Click the Add Or Remove button at the bottom.
3 - Click the Add button.
4 - Click Browse and navigate to “/Applications/Devonthink 3.app”, select it, and click Open.
5 - In Display Name, type “Devonthink” and then click OK.
6 - Click Exit and then close the preferences window.
7 - Go to Scansnap Home > Scan Settings.
8 - Click the Add Profiles button in the upper right (a circle with a “+”).
9 - In the left column, click Scan To Folder.
10 - Change the profile name to “Devonthink” and the description to “Scan to Devonthink”.
11 - Change Managing Options - Type: to Mac (Scan To File).
12 - Change Application - Send To: to Devonthink.
13 - Click Add and then close the Scan Settings window.
14 - Start Devonthink 3 and go to Devonthink 3 > Preferences > OCR.
15 - Set Convert Incoming Scans: To Searchable PDF.
16 - Check Original Document: Move To Trash. (If you don’t do this, copies of the scanned PDFs will accumulate in “~/Documents/ScanSnap Home folder”.)
17 - Close Preferences.
18 - On the Scansnap ix1500 touch screen, above the big blue Scan button is a row of blue buttons labeled Scansnap Home, Scan To Folder, etc. With your finger, swipe left until you see the Devonthink button. Tap that button to select it. (Note that the current profile selected in the Scansnap Home app is ignored when you tap Scan on the scanner’s screen.)