Why does my spreadsheet show an "illegal characters" error?
How to fix the error when your spreadsheet column headers contain characters that conflict with the mail merge engine.
Contents
What This Error Means
When you upload a spreadsheet, SecureMailMerge checks that your column headers do not contain certain character sequences. If any column header contains one of these sequences, you will see an error listing the affected columns.
Which Sequences Are Not Allowed
The following sequences cannot be used in column headers:
$${{}}{%%}
Examples
| Problematic header | Fix |
|---|---|
Price $$ | Price USD or Price (dollars) |
{{Name}} | Name |
Notes {%raw%} | Notes raw |
How to Fix It
- Open your spreadsheet in Excel, Google Sheets, or another editor
- Rename any column header that contains a forbidden sequence
- Save the spreadsheet and upload it again in SecureMailMerge
Only the header row (the first row) is restricted. The data rows below can contain any characters without issue — $$, {{, }} and so on are perfectly fine in cell values and will merge into your emails as-is.
The Error Message
When this validation fails, you will see a message similar to:
The following column headers contain characters that are not supported: “Price $$” contains $$; “{{Name}}” contains {{, }}. Column headers cannot contain: $$, {{, }}, {%, %}. Please rename the column(s) in your spreadsheet and try again.
The message lists every affected column and which sequences were found, so you know exactly what to rename.