当我尝试通过LDAP更改某个用户的密码时，在该用户的AD帐户中设置了下次登录时必须更改密码，我收到以下错误：
cause: javax.naming.AuthenticationException: [LDAP: error code 49 - 80090308: LdapErr: DSID-0C090447, comment: AcceptSecurityContext error, data 773, v3839
子代码773表示用户必须重置密码，这正是我现在要做的。
使用以下代码，如果上述标志为notset，则可以成功更改密码：

public void updateUserPassword(String user, String oldPassword,
                                   String newPassword) throws NamingException, LoginException {
        try {
            InitialDirContext ctx = this.getContext();

            String filter = "(&(objectClass=user)(sAMAccountName=" + user + "))";
            String baseDn = (String) this.getActiveDirectoryProps().get("baseDN_User");

            // Search for user entry
            SearchControls ctls = new SearchControls();
            ctls.setSearchScope(SearchControls.SUBTREE_SCOPE);
            ctls.setReturningObjFlag(true);

            String[] returnAttrs = new String[3];
            returnAttrs[0] = "cn"; // Common Name
            returnAttrs[1] = "displayName"; 
            returnAttrs[2] = "description";

            NamingEnumeration<SearchResult> enumSearchResult = ctx.search(baseDn, filter, returnAttrs, ctls);

            if (enumSearchResult.hasMore()) {
                SearchResult result = enumSearchResult.next();
        
                DirContext userCtx = (DirContext) result.getObject();

                // Change the BindUser
                ctx.addToEnvironment(Context.SECURITY_PRINCIPAL, userCtx.getNameInNamespace());
                ctx.addToEnvironment(Context.SECURITY_CREDENTIALS, oldPassword);

                // Update password
                Attribute oldattr = new BasicAttribute("unicodePwd", toUnicodeBytes(oldPassword));
                Attribute newattr = new BasicAttribute("unicodePwd", toUnicodeBytes(newPassword));
                ModificationItem olditem = new ModificationItem(DirContext.REMOVE_ATTRIBUTE, oldattr);
                ModificationItem newitem = new ModificationItem(DirContext.ADD_ATTRIBUTE, newattr);

                String dn = userCtx.getNameInNamespace();
                ctx.modifyAttributes(dn, new ModificationItem[]{olditem, newitem});
            }
            ctx.close();
        } catch (final NamingException nE) {
            //
        } catch (Exception E) {
           //
        } finally {
          //
        }
    }

那么，你是否知道有甚么地方需要改变，又或者是甚么原因令它不能运作呢？