We have our current platform set up with Akamai as the CDN, Apache as the web server, and AEM as the content tool. We had to do real-time ID verification through Signicat — which returned a huge SAML. When we get this huge amount of SAML and try to pass it to our server to parse, we always find bad SAML; it was getting truncated after a certain number of characters (around 7,800). My initial assumption was that the browser was restricting the size and hence truncating, causing a “400 — Bad request from the server" error. I searched on the internet and did not find any credible solution to my problem. After researching I found that this issue is a server-side issue, as most web servers restrict request the size to 8KB. Initially, I thought just aone server was restricting — but I realized that all three servers were.
If your request gets truncated due to its large size and you get "400 — Bad request from the server," this means that your web server, proxy, or content server is not able to handle a large amount of data. You will not find any logs in your application, as it is a server configuration issue. You need to increase the size of the server request.