I just have to report what proved to be an easy solution, not easy enough to persuade anyone from firing Intuit going forward (unless hey ACTUALLY fix the problem), but enough to get through the current tax season. I took the following steps: 1. Backup up my QB2020 data file. (Probably unnecessary, according to subsequent experience). 2. Install QB Enterprise trial edition. This is done by downloading and executing a file named QuickBooksEnterprise24Trial.exe. I was not required to enter any identifying information. A promotional video tried to entertain me but did not delay me. Mute it if it annoys you. 3. Reboot as instructed. I tried skipping that step, but TTB23 failed to import without rebooting first, so don't even try that (although it did no harm other than wasting my time). 4. Do not start QB (not Enterprise, not QB2020). Do start TTB23. That will cause you to open your data file in QB2020. Now the TTB23 import procedure works as it should with no tears. 5. You may well be home free now, but I continued as follows out of an abundance of caution and mistrust of Intuit. Uninstall QB Enterprise. Windows churned for a couple of minutes in the process of doing that. 6. Open QB2020. Restore my QB2020 data file, just in case that temporary QB Enterprise presence corrupted it somehow. But probably unnecessary. All appears to be well. 7. Open TTB23. All appears to be well after proceeding with the imported data. 8. Reboot (probably unnecessary). I just have to report what proved to be an easy solution, not easy enough to persuade anyone not to fire Intuit going forward (unless they ACTUALLY and quickly fix the problem), but enough to get through the current tax season. I took the following steps (Windows 10): 1. Backup up my QB2020 data file. (Probably unnecessary, according to subsequent experience.) 2. Install QB Enterprise trial edition. This is done by downloading and executing a file named QuickBooksEnterprise24Trial.exe. I was not required to enter any identifying information. A promotional video tried to entertain me but did not delay me. Mute it if it annoys you. 3. Reboot as instructed. I tried skipping that step, but TTB23 failed to import without rebooting first, so don't even try that (although it did no harm other than wasting my time). 4. Do not start QB (not Enterprise, not QB2020). Do start TTB23. Try again to import the AB data into TTB23. That will cause you to open your data file in QB2020, and it’s OK to do that now. The TTB23 import procedure now works as it should with no tears. 5. You may well be home free now, but I continued as follows out of an abundance of caution and mistrust of Intuit. Uninstall QB Enterprise. Windows churned for a couple of minutes in the process of doing that. 6. Open QB2020. Restore my QB2020 data file, just in case that temporary QB Enterprise presence corrupted it somehow. But probably unnecessary. All appears to be well. 7. Open TTB23. All appears to be well after proceeding with the imported data. 8. Reboot (probably unnecessary). | 
