Here is the error I got in logs
java.lang.NullPointerException: null
at java.io.PrintWriter.write(Unknown Source)
at com.adobe.granite.translation.connector.msft.core.impl.AccessTokenServlet.doPost(AccessTokenServlet.java:89) [com.adobe.granite.translation.connector.msft.core:1.3.24]
at org.apache.sling.api.servlets.SlingAllMethodsServlet.mayService(SlingAllMethodsServlet.java:146) [org.apache.sling.api:2.18.4]
at org.apache.sling.api.servlets.SlingSafeMethodsServlet.service(SlingSafeMethodsServlet.java:342) [org.apache.sling.api:2.18.4]
at org.apache.sling.api.servlets.SlingSafeMethodsServlet.service(SlingSafeMethodsServlet.java:374) [org.apache.sling.api:2.18.4]
at org.apache.sling.engine.impl.request.RequestData.service(RequestData.java:552) [org.apache.sling.engine:2.6.18]