SharePoint 2019 supports content database migration from the SharePoint 2016 environment into the SharePoint 2019 environment.

Step 1. First, take a content database backup from SP 2016. Please follow the steps below.

  1. Go to the central admin and click on “Manage Content Databases”.
    Manage Content
  2. Select the web application for which you need the content database backup.
    Content database
  3. Copy the Content Database name. Then select the Content Database.
    Content Database name
  4. Open the SQL server management studio. Expand the database. Select the database. Right-click on it. Select the Tasks > Back Up.
    SQL server
  5. It will navigate to the following window. Select the location below.
    Location below
  6. Remove this path and add the path where you want to keep your backup (.bak) file.
    Path
  7. Now, click on the OK button and wait till the backup completes successfully.
    OK button
    Studio
  8. Once complete you can see your .bak file in the location which you have set above.
    Bak file

Step 2. Create a new web application on the SP 2019 environment. To create a new web application navigate to central admin and clicks on “Manage web application”.

Manage web application

And now, click the “New” ribbon button.

Ribbon button

A modal dialog will appear. Please provide all the necessary information.

Necessary information

Now, please wait until the processing is finished.

Processing

Finally, you can see your new web application has been successfully created on your end.

Web application

After creating the web application follow these steps as mentioned below.

Under the Database Status, select the “Offline” option from the dropdown list.

Offline

Check the Check Mark in the "Remove content database" checkbox.

Remove content

A prompt will come, select OK on that. Now the content database is removed from the web application.

Step 3. Restore the 2016 database.

Step 4. Now, the time has come to associate and upgrade this content database to SP2019's newly created web application. Please use the below command to mount the database to a new web application.