There is a known issue resulting from a recent ConnectWise Patch for 2018.1 that has invalidated internal Passwords used by the Accounting API.

ConnectWise Platform Ticket: A ticket has been logged with ConnectWise (Ticket #9299516)

Partners affected by the upgrade are requested to log a support ticket with ConnectWise Support referring to Ticket #9299516 requesting update for when the patch is released for immediate update.

The following is the work-around:
  1. Log into ConnectWise
  2. Click your name at the top right of the screen
  3. Select My Account
  4. Under Password, enter your current password
  5. Enter a NEW password
    Note:
    • It is important that you change the password from what you were using previously. It's been found that even after changing the password, setting it back again will result in the same errors.
    • The password must:
      • Contain at least 1 lowercase and 1 uppercase letter.
      • Contain at least 1 number (0–9)
      • Not contain special characters (e.g. !@#$%&*)
  6. Click Save
  7. Log into Wise-Sync, and click on Users
  8. Click on your user account (or the one used to sync via the Quick Link)
  9. Click on ConnectWise Member Tab
  10. Update your new Password, and click 'Test ConnectWise Connectivity'
If the password still fails, repeat steps 3 - 6, changing the password slightly.