Event ID: 5021
Source: Windows Process Activation Service (WAS)
The identity of application pool LSGroupExpAppPool is invalid. The user name or password that is specified for the identity may be incorrect, or the user may not have batch logon rights. If the identity is not corrected, the application pool will be disabled when the application pool receives its first request. If batch logon rights are causing the problem, the identity in the IIS configuration store must be changed after rights have been granted before Windows Process Activation Service (WAS) can retry the logon. If the identity remains invalid after the first request for the application pool is processed, the application pool will be disabled. The data field contains the error number.
The issue was caused by a Group Policy that was conflicting with the rights applied by the OCS installation to the ‘Log on as a batch job’ and ‘Log on as a service’ user rights in the Local Security Policy on the OCS server.
The fix is to ensure that the RTC Service and RTCComponentService accounts have the ‘Log on as a batch job’ and ‘Log on as a service’ user rights on the OCS server. This right can be found in Local Security Policy > Computer Configuration > Windows Settings > Local Policies > User Rights Assignment. Either remove the conflicting Group Policy and fix the Local Policy or add the rights to the Group Policy.