Adding new contact getting Invalid Byte Sequence in UTF-8 error

Frequent Participant

Adding new contact getting Invalid Byte Sequence in UTF-8 error

We are working on implementing the new V3 version of your API.  When we push over a contact that has a special character in their name (in this case "Boglárka") we are receiving the "invalid byte sequence in utf-8" error.  I have code that converts the unicode to ISO-8859-1 but it still gives this error. Am I converting this string incorrectly?  I get the same issue when I add or update this contact.  Bulk import blows up the entire batch. 

Request Body:

"contact_id": null,
"email_address": {
"address": "",
"permission_to_send": "implicit"
"first_name": "Boglárka",
"last_name": "Balassaa",
"job_title": "",
"company_name": "",
"create_source": "Account",
"update_source": "Account",
"phone_numbers": [],
"street_addresses": [{
"street": "",
"city": "",
"state": "",
"postal_code": null,
"country": "",
"kind": "work"
"list_memberships": ["91ef3366-4f41-11e9-bc63-d4ae52806b34", "6bbe73a8-4f3e-11e9-8fc2-d4ae5292c973", "6bd796b2-4f3e-11e9-b034-d4ae528ed502"]


"error_key": "contacts.api.bad_request",
"error_message": "invalid byte sequence in UTF-8"

Hello @IntegrationT4,


Thank you for reaching out to Constant Contact's API Support.


Unicode or 16-bit character sets are not supported in Constant Contact. You will want to use an 8-bit character set, or you can try an HTML entity.

Jimmy D.
Tier II API Support Engineer
Occasional Participant

I'm trying to set the name of a Contact which is "Beà".

I have tried leaving it UTF-8 - I get the Invalid character error.

I tried setting the name to "Beà" (à is the HTML entity for "à") and the resulting saved name is the explicit characters "BEà".

There is no equivalent ISO-8859-1 encoding for this character.

Is there a way to get this character into the Constant Contact Name field?\

PUT (update) JSON : 


Resulting name field for GET contact:

"first_name": "Beà"



I was able to add this character to a name field in the Constant Contact website UI, though it does not seem to be supported properly with our V3 API. I have brought this to our development team to review a possible enhancement.

Please let me know if you have any other questions!


David B.
Tier II API Support Engineer

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