title: Unable to install SQL Server 2017 Express Database Engine Services
body: <p>I've been trying to install SQL Server Express 2017 for the past two days, but the installation completes with an error where the Database Engine Services and the SQL Server Replication fails to be installed. I also get this error pop-up message:</p>
  
  <p><strong>The following error has occurred:
  Object reference not set to an instance of object.</strong></p>
  
  <p>I've also tried the following steps in hopes of fixing this: 
  i)Checking and Fixing my PC's .NET v4.6 using a .NET Repair Toolkit.
  ii)Changing the SQL Server Database Engine Configuration to <strong>NT AUTHORITY\NETWORK SERVICE</strong> and also <strong>NT AUTHORITY\SYSTEM</strong>. 
  iii)Trying to repair the system after the installation using the repair tool.</p>
  
  <p>The error log from the installation: </p>
  
  <pre><code>Feature:                       Database Engine Services
  Status:                        Failed
  Reason for failure:            An error occurred during the setup process of the feature.
  Next Step:                     Use the following information to resolve the error, uninstall this feature, and then run the setup process again.
  Component name:                SQL Server Database Engine Services Instance Features
  Component error code:          -2147467261
  Error description:             Object reference not set to an instance of an object.
  Error help link:               https://go.microsoft.com/fwlink?LinkId=20476&amp;ProdName=Microsoft+SQL+Server&amp;EvtSrc=setup.rll&amp;EvtID=50000&amp;ProdVer=14.0.1000.169&amp;EvtType=0x9C8C9C81%400x44A889F9&amp;EvtType=0x9C8C9C81%400x44A889F9
  
  Feature:                       SQL Server Replication
  Status:                        Failed
  Reason for failure:            An error occurred for a dependency of the feature causing the setup process for the feature to fail.
  Next Step:                     Use the following information to resolve the error, uninstall this feature, and then run the setup process again.
  Component name:                SQL Server Database Engine Services Instance Features
  Component error code:          -2147467261
  Error description:             Object reference not set to an instance of an object.
  Error help link:               https://go.microsoft.com/fwlink?LinkId=20476&amp;ProdName=Microsoft+SQL+Server&amp;EvtSrc=setup.rll&amp;EvtID=50000&amp;ProdVer=14.0.1000.169&amp;EvtType=0x9C8C9C81%400x44A889F9&amp;EvtType=0x9C8C9C81%400x44A889F9
  
  and the error log after repairing the instance: 
  
  Feature:                       Database Engine Services
  Status:                        Failed
  Reason for failure:            An error occurred during the setup process of the feature.
  Next Step:                     Use the following information to resolve the error, and then try the setup process again.
  Component name:                SQL Server Database Engine Services Instance Features
  Component error code:          0x84B40002
  Error description:             The SQL Server feature 'SQL_Engine_Core_Inst' is not in a supported state for repair, as it was never successfully configured. Only features from successful installations can be repaired. To continue, remove the specified SQL Server feature.
  Error help link:               https://go.microsoft.com/fwlink?LinkId=20476&amp;ProdName=Microsoft+SQL+Server&amp;EvtSrc=setup.rll&amp;EvtID=50000&amp;ProdVer=14.0.1000.169&amp;EvtType=0x2841E06E%401204%402&amp;EvtType=0x2841E06E%401204%402
  
  Feature:                       SQL Server Replication
  Status:                        Failed
  Reason for failure:            An error occurred for a dependency of the feature causing the setup process for the feature to fail.
  Next Step:                     Use the following information to resolve the error, and then try the setup process again.
  Component name:                SQL Server Database Engine Services Instance Features
  Component error code:          0x84B40002
  Error description:             The SQL Server feature 'SQL_Engine_Core_Inst' is not in a supported state for repair, as it was never successfully configured. Only features from successful installations can be repaired. To continue, remove the specified SQL Server feature.
  Error help link:               https://go.microsoft.com/fwlink?LinkId=20476&amp;ProdName=Microsoft+SQL+Server&amp;EvtSrc=setup.rll&amp;EvtID=50000&amp;ProdVer=14.0.1000.169&amp;EvtType=0x2841E06E%401204%402&amp;EvtType=0x2841E06E%401204%402
  </code></pre>
  
  <p>It would be great if someone can suggest me new solutions to troubleshoot this problem as soon as problem. (Totally new to MS SQL Server,though)</p>