DTRACE for EVSVR shows the following lines.

[19844]  (evsvr)  <4804>  EV:L  {COperation::VaultStoreGroupHasFPDB} (Exit) Status: [Success]
[19844]  (evsvr)  <4804>  EV:L  {COperation::CanConnectToDB} (Entry) SQLServer: YE2433.DANSKENET.NET, Database: EVVSGEMEAVSGJNL02_5_5
[19844]  (evsvr)  <4804>  EV:M  COperation::CanConnectToDB - Open: 0x80004005, ADO Errors returned: SSL Provider: The target principal name is incorrect.|Client unable to establish connection. For solutions related to encryption errors, see https://go.microsoft.com/fwlink/?linkid=2227882.
[19844]  (evsvr)  <4804>  EV:H  {COperation::CanConnectToDB:#3174} _com_error exception: [<0x800a0e78>]
[19844]  (evsvr)  <4804>  EV:H  {COperation::CanConnectToDB} (Exit) Status: [<0x800a0e78>]
[19844]  (evsvr)  <4804>  EV:H  {COperation::CheckFPCDB:#2649} _com_error exception: [<0x800a0e78>]
[19844]  (evsvr)  <4804>  EV:H  {COperation::CheckFPCDB} (Exit) Status: [<0x800a0e78>]
[19844]  (evsvr)  <4804>  EV:H  {COperation::DoDBAndPartitionChecks:#2537} _com_error exception: [<0x800a0e78>]
[19844]  (evsvr)  <4804>  EV:L  CLogFile::Write - [ (null) | (null) | The EVSVR initial operation checks failed | Error: <0x800a0e78> | (null) ]

Enterprise Vault 15.1 uses the Microsoft OLE DB Driver for SQL Server version 19.x. By default, OLE DB Driver 19.x strictly enforces connection encryption (Encrypt=yes).

To resolve this issue, use one of the following methods depending on your security policies.

Method 1: Install a Valid TLS/SSL Certificate (Recommended)

a. Ensure that the SQL Server uses a valid, commercially signed or internal Certificate Authority (CA) issued certificate. 
b. The certificate must match the fully qualified domain name (FQDN) of the SQL Server.
c. Install the matching root and intermediate CA certificates into the Trusted Root Certification Authorities store on the Enterprise Vault server.

Method 2: Disable Forced Encryption in SQL Server (Alternative)

If your environment does not strictly require encrypted database traffic, disable forced encryption on the database server.

a. Log into the SQL Server Management Studio.
b. Open SQL Server Configuration Manager.
c. Expand SQL Server Network Configuration.
d. Right-click Protocols for [Your_Instance_Name] and select Properties.
e. On the Flags tab, change Force Encryption from Yes to No.
f. Click Apply and restart the SQL Server service

When running the (EVSVR) utility in Veritas Enterprise Vault 15.1, the operation fails immediately during the initial startup checks.