Just saw this come up in the forum feed and thought this is likely tied to CoBubble’s text messaging plugin. There are quite a few apps using this plugin with no issues reported, so perhaps your’s are isolated occurrences. Something interesting to note about that error code is that it’s actually the plugin’s unique ID in the Bubble system. Go through the plugin instructions and double check if everything is in order. I can definitely see simple things like encoding or adding the ‘Basic’ to the call header as easy to miss.
Feel free to give me a shout if you still experience issues!