3070148 - Diagnostics agent can not be trusted as the secstore.properties file is corrupted

The smdsetup script is failing with the error:

smdsetup managingconf hostname:"sapms://<solman.full.qual.host.name>" port:"<81xx>"

parameter 'managingconf' ignored because of missing value

------- Prerequisites ----------
 - Java version OK.
 - Agent certificate check ERROR:
 -- Agent certificate expired at: <xxxxx>
Prerequisite Check: FAILED

Or the diagnostics agent can not be trusted as the secstore.properties file is corrupted with the agent logs showing the error:

"Cannot find smd/agent/secretkey in configuration/secstore.properties. Returning null."

or

Generating certificate failed.
[EXCEPTION]
java.rmi.RemoteException: Could not generate certificate; nested exception is: 
    com.sap.smd.server.manager.SMDException: Failed to retrive certificate with alias ssl-certificate
    at com.sap.smd.agent.connection.configuration.ManagingConnectionManipulator.generateCertificate(ManagingConnectionManipulator.java:1010)
    at com.sap.smd.agent.AgentContext.generateCertificate(AgentContext.java:585)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at com.sap.engine.services.rmi_p4.P4DynamicSkeleton.dispatch(P4DynamicSkeleton.java:241)
    at com.sap.engine.services.rmi_p4.DispatchImpl._runInternal(DispatchImpl.java:483)
    at com.sap.engine.services.rmi_p4.DispatchImpl._run(DispatchImpl.java:282)
    at com.sap.engine.services.rmi_p4.DispatchImpl.run(DispatchImpl.java:759)
    at java.lang.Thread.run(Thread.java:838)
Caused by: com.sap.smd.server.manager.SMDException: Failed to retrive certificate with alias ssl-certificate
    at com.sap.smd.util.AgentCertificateManager.storeCertificate(AgentCertificateManager.java:534)
    at com.sap.smd.util.AgentCertificateManager.generateCredentials(AgentCertificateManager.java:715)
    at com.sap.smd.agent.connection.configuration.ManagingConnectionManipulator.generateCertificate(ManagingConnectionManipulator.java:1005)
    ... 10 more
Caused by: com.sap.smd.server.manager.SMDException: Could not get the certificate key from secure storage
    at com.sap.smd.util.AgentCertificateManager.getCertificateKeyOfStorage(AgentCertificateManager.java:91)
    at com.sap.smd.util.AgentCertificateManager.getAgentKeyStore(AgentCertificateManager.java:346)
    at com.sap.smd.util.AgentCertificateManager.getAgentKeyStore(AgentCertificateManager.java:333)
    at com.sap.smd.util.AgentCertificateManager.storeCertificate(AgentCertificateManager.java:528)
    ... 12 more
Caused by: java.lang.IllegalArgumentException: Illegal base64 character d
    at java.util.Base64$Decoder.decode0(Base64.java:722)
    at java.util.Base64$Decoder.decode(Base64.java:534)
    at java.util.Base64$Decoder.decode(Base64.java:557)
    at com.sap.security.core.server.secstorefs.base64.Base64ConverterJVM.decodeString(Base64ConverterJVM.java:57)
    at com.sap.security.core.server.secstorefs.StorageHandler.getValue(StorageHandler.java:464)
    at com.sap.security.core.server.secstorefs.SecStoreHandler.getStringValue(SecStoreHandler.java:483)
    at com.sap.security.core.server.secstorefs.SecStoreFS.getStringValue(SecStoreFS.java:267)
    at com.sap.smd.util.AgentCertificateManager.getCertificateKeyOfStorage(AgentCertificateManager.java:78)
    ... 15 more

• SAP Solution Manager 7.2
• Unix and Windows OS

DAA, secstore.properties, secretkey, corrupt , KBA , SV-SMG-DIA-SRV-AGT , Agent Framework , Problem