I am now getting 404 errors on 90% of the calls searching for companies by number.
Without examples I wouldn’t know. A speculation - if this occurs when requesting company info e.g. “company profile” or other endpoint (e.g. not the search endpoint) check the actual URI sent to Companies House contains 8 characters - e.g. leading zeros are not being dropped, no spaces before / after:
e.g. if your company is number 09824208 ensure you’re sending
…/company/09824208
and not:
/company/9824208
The entries returned by the API in “links” sections should be correct but if these company numbers are coming from anywhere else don’t assume they’re correct!.
This may be of no consequence to you but I had a quick look at the Python wrapper you’re using and it looks like if CH returns a http error the wrapper will always complain about these headers being missing. It seems that CH do not send these headers if reporting an http error. I’m not a Python coder and this was only a skim read so I maybe wrong!