Sling POST servlet HTTP 500 error. POST parameters are being scrambled.

Are you posting to a custom Servlet?

No, this is just posting directly to the page node using the default sling servlet

I was hoping it was a custom servlet - that way you could log the parameters. As you are using the default POST servlet - you cannot really log messages. Let see if other community members have seen this. If you fo not hear anything - open a ticket. This should not  be occurring.

Will it be possible to provide a sample code for us to troubleshoot ?

It's really hard to diagnose what's happening here without logs. You can use Apache Sling :: Log Tracer  to trace the request logs for your specific path and it provides fine control over request logging. It might help give you an idea of what is happening. You can also use Apache Sling :: Request Processing Analyzer (reqanalyzer)  to analyze the requests and see if there are any filters that modify the request before it reaches the default sling servlet. hope this helps!

Thanks, i'll take a look at that logging config and see if that helps at all. I did try to enable debug logging for - org.apache.sling.servlets.post.impl - to see if i could get anything out of that, but it wasn't too helpful.

Will have to think about sample code, it's really not much more than sending that POST request to the server as i have confirmed the POST request looks good when it leaves the browser.

At this point i think my only options left to pursue are opening a ticket and attempting to write a custom servlet that mimics the default POST servlet.

Oh, yes that's a great idea, thank you! That will at least let me debug whether the issue lies within the default servlet or on the network before it gets to AEM.

Here's what i ended up finding - I created the filter for logging as atyaf66 suggested and i could see that the POST request is being truncated before it gets to AEM. Here's an example of a working call and the bad call -

vs

So something is just removing the first part of the POST body. Will have to identify what in our network would allow that to happen. Thanks for the support!

Here is the filter i ended up throwing together -

@Component(immediate=true, enabled=true)
@Service(value=Filter.class)
@Properties({
    @Property(name="sling.filter.scope", value="REQUEST", propertyPrivate=true),
    @Property(name="service.ranking", intValue=1000001, propertyPrivate=true)
})
public class ParamPostFilter implements javax.servlet.Filter {
    Logger log = LoggerFactory.getLogger(this.getClass());
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain filterChain) throws IOException, ServletException {
        HttpServletRequest httpRequest = (HttpServletRequest)request;
        
        try {
            if (httpRequest.getMethod().equalsIgnoreCase("POST")) {
                log.debug("********* Caught POST **********");
                
                Enumeration<String> params = request.getParameterNames(); 
                StringBuilder sb = new StringBuilder();
                
                while(params.hasMoreElements()){
                    String paramName = params.nextElement();
                    String[] paramValues = request.getParameterValues(paramName);
    
                     for (int k = 0; k < paramValues.length; k++) {
                         sb.append(paramName + "=" + paramValues[k] + "&");
                     }
                }
                
                log.debug(sb.toString());
            }
        } catch (Exception e) {
            log.error("POST filter failure", e);
        }
        
        filterChain.doFilter(request, response);
    }
}