Dashboard doesn't load due to error response from /pdb/dashboard/data

Today after upgrading from puppetdb-6.7.1-1.el7.noarch to puppetdb-6.11.3-1.el7.noarch on RHEL76 host, the following error messages start showing up all the time, and now pdb/jetty is not working at all. The basic function for puppetdb seems to be still working, just its dashboard is now down. 

it seems this error matching this earlier issue from long time ago: https://tickets.puppetlabs.com/si/jira.issueviews:issue-html/PDB-3312/PDB-3312.html

Any workaround for this one? 

2020-08-19T10:52:29.435-05:00 WARN [o.e.j.s.HttpChannel] /pdb/dashboard/data
java.lang.ClassCastException: java.lang.String cannot be cast to java.lang.Number
at clojure.lang.Numbers.multiply(Numbers.java:173)
at puppetlabs.puppetdb.dashboard$fn_42532$get_dashboard_data42537$fn42538$iter4253942543$fn42544$fn_42545.invoke(dashboard.clj:162)
at puppetlabs.puppetdb.dashboard$fn_42532$get_dashboard_data42537$fn42538$iter4253942543$fn_42544.invoke(dashboard.clj:158)
at clojure.lang.LazySeq.sval(LazySeq.java:42)
at clojure.lang.LazySeq.seq(LazySeq.java:51)
at clojure.lang.RT.seq(RT.java:535)
at clojure.core$seq__5402.invokeStatic(core.clj:137)
at clojure.core$seq__5402.invoke(core.clj:137)
at schema.spec.collection$element_transformer$fn__3840.invoke(collection.clj:26)
at schema.spec.collection.CollectionSpec$fn__3880.invoke(collection.clj:79)
at clojure.core$comp$fn__5807.invoke(core.clj:2569)
at puppetlabs.puppetdb.dashboard$fn_42532$get_dashboard_data_42537.invoke(dashboard.clj:156)
at puppetlabs.puppetdb.dashboard$build_app$fn__42568.invoke(dashboard.clj:171)
at bidi.ring$fn__32322.invokeStatic(ring.cljc:25)
at bidi.ring$fn__32322.invoke(ring.cljc:21)
at bidi.ring$fn_32307$G32302_32316.invoke(ring.cljc:16)
at puppetlabs.puppetdb.middleware$fn_33208$make_pdb_handler33217$fn33220$fn_33222.invoke(middleware.clj:397)
at compojure.core$routing$fn__1859.invoke(core.clj:151)
at clojure.core$some.invokeStatic(core.clj:2701)
at clojure.core$some.invoke(core.clj:2692)
at compojure.core$routing.invokeStatic(core.clj:151)
at compojure.core$routing.doInvoke(core.clj:148)
at clojure.lang.RestFn.invoke(RestFn.java:423)
at puppetlabs.puppetdb.pdb_routing$wrap_with_context$fn__46395.invoke(pdb_routing.clj:34)
at compojure.core$if_context$fn__1883.invoke(core.clj:218)
at compojure.core$routing$fn__1859.invoke(core.clj:151)
at clojure.core$some.invokeStatic(core.clj:2701)
at clojure.core$some.invoke(core.clj:2692)
at compojure.core$routing.invokeStatic(core.clj:151)
at compojure.core$routing.doInvoke(core.clj:148)
at clojure.lang.RestFn.applyTo(RestFn.java:139)
at clojure.core$apply.invokeStatic(core.clj:667)
at clojure.core$apply.invoke(core.clj:660)
at compojure.core$routes$fn__1863.invoke(core.clj:156)
at compojure.core$routing$fn__1859.invoke(core.clj:151)
at clojure.core$some.invokeStatic(core.clj:2701)
at clojure.core$some.invoke(core.clj:2692)
at compojure.core$routing.invokeStatic(core.clj:151)
at compojure.core$routing.doInvoke(core.clj:148)
at clojure.lang.RestFn.invoke(RestFn.java:460)
at puppetlabs.puppetdb.pdb_routing$pdb_app$fn__46406.invoke(pdb_routing.clj:62)
at compojure.core$if_context$fn__1883.invoke(core.clj:218)
at ring.middleware.params$wrap_params$fn__31437.invoke(params.clj:64)
at puppetlabs.puppetdb.middleware$wrap_with_certificate_cn$fn__33043.invoke(middleware.clj:78)
at puppetlabs.puppetdb.middleware$wrap_with_default_body$fn__33048.invoke(middleware.clj:85)
at puppetlabs.puppetdb.middleware$wrap_with_debug_logging$fn__33026.invoke(middleware.clj:42)
at puppetlabs.i18n.core$locale_negotiator$fn__124.invoke(core.clj:357)
at puppetlabs.trapperkeeper.services.webserver.jetty9_core$ring_handler$fn__48002.invoke(jetty9_core.clj:455)
at puppetlabs.trapperkeeper.services.webserver.jetty9_core.proxy$org.eclipse.jetty.server.handler.AbstractHandler$ff19274a.handle(Unknown Source)
at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:127)
at org.eclipse.jetty.server.handler.ScopedHandler.nextHandle(ScopedHandler.java:235)
at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1363)
at org.eclipse.jetty.server.handler.ScopedHandler.nextScope(ScopedHandler.java:190)
at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1278)
at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:141)
at org.eclipse.jetty.server.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:221)
at org.eclipse.jetty.server.handler.HandlerCollection.handle(HandlerCollection.java:146)
at org.eclipse.jetty.server.handler.gzip.GzipHandler.handle(GzipHandler.java:767)
at org.eclipse.jetty.server.handler.RequestLogHandler.handle(RequestLogHandler.java:54)
at com.puppetlabs.trapperkeeper.services.webserver.jetty9.utils.MDCRequestLogHandler.handle(MDCRequestLogHandler.java:36)
at org.eclipse.jetty.server.handler.StatisticsHandler.handle(StatisticsHandler.java:173)
at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:127)
at org.eclipse.jetty.server.Server.handle(Server.java:500)
at org.eclipse.jetty.server.HttpChannel.lambda$handle$1(HttpChannel.java:383)
at org.eclipse.jetty.server.HttpChannel.dispatch(HttpChannel.java:547)
at org.eclipse.jetty.server.HttpChannel.handle(HttpChannel.java:375)
at org.eclipse.jetty.server.HttpConnection.onFillable(HttpConnection.java:273)
at org.eclipse.jetty.io.AbstractConnection$ReadCallback.succeeded(AbstractConnection.java:311)
at org.eclipse.jetty.io.FillInterest.fillable(FillInterest.java:103)
at org.eclipse.jetty.io.ChannelEndPoint$2.run(ChannelEndPoint.java:117)
at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.runTask(EatWhatYouKill.java:336)
at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.doProduce(EatWhatYouKill.java:313)
at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.tryProduce(EatWhatYouKill.java:171)
at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.run(EatWhatYouKill.java:129)
at org.eclipse.jetty.util.thread.ReservedThreadExecutor$ReservedThread.run(ReservedThreadExecutor.java:375)
at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:806)
at org.eclipse.jetty.util.thread.QueuedThreadPool$Runner.run(QueuedThreadPool.java:938)
at java.lang.Thread.run(Thread.java:748)