I’m trying to upload a decision table using an Excel template in Appian 22.4, but I keep getting an ‘unsupported format’ error during import. The file is .xlsx format and follows what I believe is the correct template structure with condition columns and action columns.
The error appears right after file selection:
ERROR: Unsupported format detected
File: DecisionTable_v3.xlsx
Expected: Valid decision table structure
I’ve verified the Excel file opens correctly and has the proper headers. The validation seems to fail before even reading the actual decision logic. This is blocking our rule deployment for a critical compliance workflow that needs to go live next week. Has anyone encountered this issue with decision table imports?
Another common issue is special characters or formatting in column headers. The decision table import expects exact naming conventions. For example, condition columns must follow the pattern ‘Condition 1’, ‘Condition 2’, etc., and action columns must be ‘Action 1’, ‘Action 2’. Any deviation like ‘Condition-1’ or extra spaces will trigger validation errors. Also verify your Excel file isn’t corrupted by opening it in a different spreadsheet application.
I’ve seen this before. Check if your Excel file has any merged cells in the header row or hidden columns. Appian’s decision table import is very strict about the file structure and doesn’t handle merged cells well. Also make sure you’re using the exact template downloaded from the Decision Management interface.
That file size is definitely suspicious. Excel files can contain hidden worksheets, cached data, or embedded objects that interfere with Appian’s parser. Try this: open your Excel file, go to File > Info > Check for Issues > Inspect Document, and remove any hidden content. Then save as a new file and try importing again. Also, make sure you’re only using basic data types in your cells - no rich text formatting or custom number formats.
Thanks for the tip. I checked and there are no merged cells, but I did create the template manually instead of downloading it from Appian. I’ll try with the official template. Should the template version match my Appian version exactly, or is there backward compatibility?
I downloaded a fresh template from our Appian 22.4 instance and still getting the error. I noticed the file size is unusually large (2.3MB) for what should be a simple decision table with only 15 rules. Could there be hidden content causing validation issues?