Thank you Hugo & foxt. I also was getting error codes 7 & 35 99.9% of the time for several weeks. I just changed from https to http connections to post my data and 99.9% success now! (Received 1 502 “The server returned an invalid or incomplete response.”)
Hi there, i have also encountered problems from 2. jan with (data.sparkfun.com) didn’t get eny error code thou just no response, but changing to http got it working.
Thanks for the tip.
I dug some more, and… it appears to be Sparkfun doing some sort of rate limiting on traffic from our developer imp server.
An identical curl call on other non-developer servers in our cluster (using the example on the data.sparkfun.com main page, ie curl “https://data.sparkfun.com/input/Jxyjr7DmxwTD5dG1D1Kv?private_key=gzgnB4VazkIg7GN1g1qA&brewTemp=33.4”) works fine, but errors out on the server that’s doing all the developer traffic.
I posted on the data.sparkfun.com forums asking them about that. If they think our IP is just one very enthusiastic hobbyist with a lot of data to post, I can see why they might limit it 
Thanks again Hugo. I got a response over on the data.sparkfun forums, but it didn’t shed any real insight. I hope the action you are taking resolves this issue so that we can go back to using https …
Unfortunately not, see https://discourse.electricimp.com/discussion/4100/data-sparkfun-com-https-non-functional-error-35#latest
…essentially they’ve said we’re sending too much traffic to them 
Thanks for your fantastic follow-through on this one.