We're running an API with quite a few people using it. Due to some legacy clumsiness on my part, one of the endpoints is returning the wrong content-type header,
js when it should be
json. My question is, if we fix this by swapping to return the correct value, how badly could it mess things up for our existing customers? Or to put it another way, would you expect many different HTTP client libraries to throw fatal errors when seeing such a change?
We're trying to decide if this is a change which we can just go ahead and make without sweating it too much, or we should carefully email all users and announce a multi-year deprecation period ...or something in between.
It probably depends a bit on what kind of different HTTP clients are in use, so I took a look at user agents. Answer: a lot of different ones! Here's some of the top ones:
"okhttp/3.2.0", "python-requests/2.10.0", "Ruby", "python-requests/2.7.0", "Mozilla/5.0", "Java/1.8.0_91", "python-requests/2.4.3", "okhttp/3.3.0", "Lucee", "Dalvik/2.1.0", "Google-HTTP-Java-Client/1.21.0", "PHP_appname", "NativeHost", "Java/1.7.0_67", "Apache-HttpClient/UNAVAILABLE", "Dalvik/1.6.0", "Web-sniffer/1.1.0", "unirest-objc/1.1"
Most people don't seem to notice that the content-type is wrong, but every now and then a new support request pops up complaining about this issue, so we'd like to fix it.