HTTP 400 Error when using API

HTTP 400 Error when using API

Hi, I'm trying to upload data through the API calls, about 80% of the time this works but the other 20% of calls return HTTP 400 errors. If the program waits 10 seconds and retries the identical data, it works. Unfortunately this makes importing data extremely slow. Is there a limit to how many calls can be executed and what is the maximum upload size? I have noticed the chance of it occurring is bigger if you upload more lines at once, but it can also give you an error when uploading as few as 10.