Hi @Muhammed Shehim ,
As we discussed in this thread: Migrated from MSDN Exchange Dev Exchange Server 2016 ecp and owa not opening-http 500 internal server error
Could you please check the application log when failed login the ECP and OWA page, share the error logs here which will be helpful to troubleshooting this issue.
If you get event id like 1309, check the SharedWebConfig.config are located in below paths
C:\Program Files\Microsoft\Exchange Server\V15\FrontEnd\HttpProxy
C:\Program Files\Microsoft\Exchange Server\V15\ClientAccess
resolution here to generate the missing file.
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