WhatsApp error 131009: Parameter value is not valid

Code 131009 means the request had the right fields but at least one value is outside what the endpoint accepts. It complements 131008 (missing field) and 100 (unknown field). The messaging layer recognized the parameter and rejected its content: an unsupported type string, a recipient that does not parse as a phone number, a media ID that does not exist, a language code the template does not have, or a value that exceeds a documented length.

Meta's documentation adds a specific hint for this code: if the invalid value is a phone number, see the phone numbers documentation for how to add a number to a WhatsApp Business Account, which tells you the check also covers sender numbers, not just recipients. In the Marketing Messages API context the same code is returned while a template is still syncing to an ad, which can take up to ten minutes.

It is not a permissions or quality problem, and the same input will fail consistently until corrected.

Validate and normalize inputs at the boundary of your system: phone numbers on write, template locale from a cached list of approved templates, media IDs with their upload timestamps so expiry is known. Keep a table of documented maximums and enforce them before building the request so the platform never sees an out-of-range value. Template-specific value problems have their own codes - 132001 for the name-language pair, 132012 for parameter formats - and template payloads can be validated with the template checker before sending.