diff -r 7281bdf43c60 -r a7e543ab0c5f src/main/java/de/uapcore/lightpit/modules/ProjectsModule.java
--- a/src/main/java/de/uapcore/lightpit/modules/ProjectsModule.java	Thu Oct 22 11:06:15 2020 +0200
+++ b/src/main/java/de/uapcore/lightpit/modules/ProjectsModule.java	Thu Oct 22 12:00:34 2020 +0200
@@ -511,7 +511,11 @@
             resp.sendError(HttpServletResponse.SC_FORBIDDEN, "Detected manipulated form.");
             return ResponseType.NONE;
         }
-        final var issue = new Issue(issueIdParam.get());
+        final var issue = dao.getIssueDao().find(issueIdParam.get());
+        if (issue == null) {
+            resp.sendError(HttpServletResponse.SC_NOT_FOUND);
+            return ResponseType.NONE;
+        }
         try {
             final var issueComment = new IssueComment(getParameter(req, Integer.class, "commentid").orElse(-1), issue);
             issueComment.setComment(getParameter(req, String.class, "comment").orElse(""));