If you are using WhatsApp interactive carousel messages, you may see an error saying that your button label is too long, even though it looks like it respects the 20-character limit.
This can be confusing especially if everything looks correct.
Here’s a simple explanation of what’s happening and how to avoid it.
The most important thing to know
👉 For WhatsApp carousel messages, Meta does NOT count characters — it counts bytes.
Some characters (such as accented letters) take more than one byte.
Why does this cause an issue?
In many languages (French, Spanish, Portuguese, etc.), we often use accented characters:
é, è, à, ç, ñ, ô, …
For us, these are 1 character.
But for WhatsApp, they can count as 2 bytes (or more).
As a result:
A button label that appears to be 20 characters
Can actually be more than 20 bytes
And WhatsApp will reject the message, so it is never sent
A simple example
Button label | Visible characters | WhatsApp byte count |
| 8 characters | 9 bytes |
| 20 characters | ❌ more than 20 bytes |
| 20 characters | ✅ 20 bytes |
👉 Accents and special characters make the difference.
Why does this only affect carousel messages?
This byte-based limit applies only to:
URL buttons
Inside interactive carousel messages
For all other WhatsApp message types, Meta counts regular characters, not bytes.
What we changed in our product
To prevent this issue:
✅ We now display the byte count for carousel URL button labels
⚠️ A clear error message appears if the limit is exceeded
📖 The error links to this article for more explanation
This helps you immediately see when a label might be blocked by WhatsApp.