Metafield keys: restrictions on special characters?

[John_Hardin]

Folks:

We're getting a "metafields.key must be unique within this namespace on this resource" error attempting to update metafields on a product via the REST API.

The key values are indeed unique; however, they share a common prefix that contains an "&" character. For example:

• mumble&mumble_key1
• mumble&mumble_key2

Is this perhaps causing the key text after the "&" (the unique part) to be ignored?

Are there special characters which should not appear in metafield keys? There is no mention of such restrictions that I have found yet in the Metafields API documentation...

Or are there perhaps key length limitations that are truncating the keys before the unique part is reached?

Thanks!

[PaulNewton]

Test Urlencoding the ampersands for a change in situation.

[John_Hardin]

We can certainly try sanitizations, but needing something like UrlEncode() on the key value should be documented...