REST/json Angular/Grails HTTP PUT (update) "Internal Server Error" 500 - json

Question

I had tested a sample app with REST/json/Grails on one end & Angular on one end to proof test the flow. It was working perfectly fine. All of HTTP GET, POST, PUT, & DELETE was fine.
Now I am making JSON requests via REST in a full-blown app for Project Management. It has basic class structure for the app: classes on Project, Contract, Contacts, Projects Roles etc.
While updating any & every record in the database (MySql 5.6 Community, Grails 2.4.3) via HTTP PUT (with PUT only, POSt with identical arguments works perfectly fine) REST/JSON, I am getting the following error (on the client side):
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Error 500: Internal Server Error URI/apaNew/api/v1/projectTasks/3Classjava.lang.NullPointerExceptionMessagenull
Around line 198 of PageFragmentCachingFilter.java 195: if (CollectionUtils.isEmpty(cacheOperations)) {196: log.debug("No cacheable annotation found for {}:{} {}",197: new Object[] { request.getMethod(), request.getRequestURI(), getContext() });198: chain.doFilter(request, response);199: return;200: }201:
Around line 63 of AbstractFilter.java 60: try {61: // NO_FILTER set for RequestDispatcher forwards to avoid double gzipping62: if (filterNotDisabled(request)) {63: doFilter(request, response, chain);64: }65: else {66: chain.doFilter(req, res);
Around line 82 of CorsFilter.java 79: }80: }81: }82: filterChain.doFilter(request, response);83: }84:85: private boolean checkOrigin(HttpServletRequest req, HttpServletResponse resp) {
Trace
Line | Method ->> 198 | doFilter in PageFragmentCachingFilter.java
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
| 63 | doFilter in AbstractFilter.java
| 82 | doFilter in CorsFilter.java
| 1145 | runWorker in java.util.concurrent.ThreadPoolExecutor
| 615 | run . . . in java.util.concurrent.ThreadPoolExecutor$Worker ^ 745 | run in java.lang.Thread
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The application is a very simple project management app. It has a Project class whose records I am trying to modify.
It was working absolutely fine in a sample app I had written before to test everything. Only after converting it into a full-blown app the problem has surfaced.
The HTTP POST/GET/DELETE request is working perfectly fine. An HTTP POST request with similar parameters is working perfectly fine.