After i installed Pega 8.4 and 8.5 PR i couldn't open the servers. I already have jdk & tomcat. At also i already did increase jvm memory, closing Windows defender, adding system name as prpc etc.. I think problem about with the sql server but don't know how to fix it. Error message and Log files below. Please help me with that issue. 

HTTP Status 503 – Service Unavailable

Type Status Report

Message PegaRULES server not available

Description The server is currently unable to handle the request due to a temporary overload or scheduled maintenance, which will likely be alleviated after some delay.

Apache Tomcat/8.5.14

2021-01-15 18:41:38,967 [ervice-registry-task] [          ] [                    ] [                    ] (    mgmt.base.NodeRequestorMgt) ERROR   - Caught exception while retrieving Data-Admin-System instance "pega" com.pega.pegarules.pub.database.MultipleInstancesWithKeyException: Database-MultipleInstancesWithKey-External    pxObjClass = "Data-Admin-System", pySystemName = "prpc"     at com.pega.pegarules.data.internal.store.AutoCommitTransaction.getResultFromResultSet(AutoCommitTransaction.java:504) ~[prprivate-data.jar:?]     at com.pega.pegarules.data.internal.store.AutoCommitTransaction.performQuery(AutoCommitTransaction.java:359) ~[prprivate-data.jar:?]     at com.pega.pegarules.data.internal.access.Opener$1.getResultPageFromDatabase(Opener.java:760) ~[prprivate-data.jar:?]     at com.pega.pegarules.data.internal.access.Opener$1.action(Opener.java:745) ~[prprivate-data.jar:?]     at com.pega.pegarules.data.internal.access.Opener$1.action(Opener.java:742) ~[prprivate-data.jar:?]     at com.pega.pegarules.data.internal.store.DataStoreManager.readInTransaction(DataStoreManager.java:74) ~[prprivate-data.jar:?]     at com.pega.pegarules.data.internal.access.Opener.openResultFromDatabase(Opener.java:771) ~[prprivate-data.jar:?]     at com.pega.pegarules.data.internal.access.Opener.openData(Opener.java:715) ~[prprivate-data.jar:?]     at com.pega.pegarules.data.internal.access.Opener.open(Opener.java:2176) ~[prprivate-data.jar:?]     at com.pega.pegarules.data.internal.access.DatabaseImpl.open(DatabaseImpl.java:2605) ~[prprivate-data.jar:?]     at com.pega.pegarules.data.internal.access.DatabaseImpl.open(DatabaseImpl.java:2566) ~[prprivate-data.jar:?]     at com.pega.pegarules.session.internal.mgmt.base.NodeRequestorMgt.createNewSystemNameRecord(NodeRequestorMgt.java:703) ~[prprivate-session.jar:?]     at com.pega.pegarules.session.internal.mgmt.base.NodeRequestorMgt.getOrCreateDataAdminSystemNameInstance(NodeRequestorMgt.java:681) ~[prprivate-session.jar:?]     at com.pega.pegarules.session.internal.mgmt.base.NodeRequestorMgt.fetchRequestorTypeInfoFromDB(NodeRequestorMgt.java:617) ~[prprivate-session.jar:?]     at com.pega.pegarules.session.internal.mgmt.base.NodeRequestorMgt.getOrCreateRequestorData(NodeRequestorMgt.java:604) ~[prprivate-session.jar:?]     at com.pega.pegarules.session.internal.mgmt.base.NodeRequestorMgt.getDataForRequestor(NodeRequestorMgt.java:590) ~[prprivate-session.jar:?]     at com.pega.pegarules.session.internal.authorization.SessionAuthorization.reset(SessionAuthorization.java:363) ~[prprivate-session.jar:?]     at com.pega.pegarules.session.internal.authorization.SessionAuthorization.<init>(SessionAuthorization.java:147) ~[prprivate-session.jar:?]     at com.pega.pegarules.session.internal.mgmt.PRRequestorBase.allocateSessionAuthorization(PRRequestorBase.java:548) ~[prprivate-session.jar:?]     at com.pega.pegarules.session.internal.mgmt.PRRequestorImpl.allocateSessionAuthorization(PRRequestorImpl.java:2289) ~[prprivate-session.jar:?]     at com.pega.pegarules.session.internal.authorization.Authorization.reset(Authorization.java:258) ~[prprivate-session.jar:?]     at com.pega.pegarules.session.internal.authorization.Authorization.reset(Authorization.java:196) ~[prprivate-session.jar:?]     at com.pega.pegarules.session.internal.authorization.Authorization.onBeforeThreadUse(Authorization.java:1779) ~[prprivate-session.jar:?]     at com.pega.pegarules.session.internal.mgmt.base.ThreadPassivation.configureThreadImpl(ThreadPassivation.java:344) ~[prprivate-session.jar:?]     at com.pega.pegarules.session.internal.mgmt.PRThreadBase.configureThread(PRThreadBase.java:184) ~[prprivate-session.jar:?]     at com.pega.pegarules.session.internal.mgmt.PRThreadImpl.<init>(PRThreadImpl.java:157) ~[prprivate-session.jar:?]     at com.pega.pegarules.session.internal.mgmt.PRThreadImpl.acquire(PRThreadImpl.java:182) ~[prprivate-session.jar:?]     at com.pega.pegarules.session.internal.mgmt.base.RequestorThreadSync.getOrCreateThread(RequestorThreadSync.java:195) ~[prprivate-session.jar:?]     at com.pega.pegarules.session.internal.mgmt.base.RequestorThreadSync.getOrCreateThread(RequestorThreadSync.java:171) ~[prprivate-session.jar:?]     at com.pega.pegarules.session.internal.mgmt.base.RequestorThreadSync.getOrCreateThread(RequestorThreadSync.java:167) ~[prprivate-session.jar:?]     at com.pega.pegarules.session.internal.mgmt.base.RequestorPassivation.configureRequestorImpl(RequestorPassivation.java:510) ~[prprivate-session.jar:?]     at com.pega.pegarules.session.internal.mgmt.PRRequestorBase.configureRequestor(PRRequestorBase.java:491) ~[prprivate-session.jar:?]     at com.pega.pegarules.session.internal.mgmt.PRRequestorImpl.<init>(PRRequestorImpl.java:332) ~[prprivate-session.jar:?]     at com.pega.pegarules.session.internal.mgmt.PRRequestorImpl.acquire(PRRequestorImpl.java:353) ~[prprivate-session.jar:?]     at com.pega.pegarules.session.internal.mgmt.base.MultiThreadRequestorFactory.acquire(MultiThreadRequestorFactory.java:76) ~[prprivate-session.jar:?]     at com.pega.pegarules.session.internal.mgmt.base.NodeRequestorMgt.createRequestorImpl(NodeRequestorMgt.java:1671) ~[prprivate-session.jar:?]     at com.pega.pegarules.session.internal.mgmt.PRNodeImpl.createRequestor(PRNodeImpl.java:329) ~[prprivate-session.jar:?]     at com.pega.pegarules.session.internal.PRSessionProviderImpl.borrowRequestor(PRSessionProviderImpl.java:756) ~[prprivate-session.jar:?]     at com.pega.pegarules.session.internal.PRSessionProviderImpl.borrowRequestor(PRSessionProviderImpl.java:771) ~[prprivate-session.jar:?]     at com.pega.pegarules.session.internal.PRSessionProviderImplForModules.borrowRequestor(PRSessionProviderImplForModules.java:58) ~[prprivate-session.jar:?]     at com.pega.platform.serviceregistry.internal.PrThreadFactory$PrpcThread.run(PrThreadFactory.java:63) ~[service-registry.jar:?]