The issue is customer is getting a text overflow issue with posting description field
The environment is NAV 2009 SP1
The resolution is in codeunit 14073310 (AVA Validate Call), there is a function called AvaPostCommitInv. There is local variable called OrigDocCode which is set to code(20). Change it to code(30) and see if you run into any issues with it during your testing.
The cause is text overflow issue
Note: AvaTax for Microsoft Dynamics NAV 2009 is sunsetted and no longer supported by Avalara as of April 30, 2016. This existing knowledge base documentation is available to provide known paths to resolution for documented issues. If you are using a version affected by service discontinuation and want to maintain access to Avalara Support, you’ll need to upgrade to the latest version of the integration as soon as possible