"The operation failed because an unexpected error occurred. (Result Code: 0x80131904)" (4287396)

"The operation failed because an unexpected error occurred. (Result Code: 0x80131904)."

The following error is written to SharePoint ULS logs:

Database full error on SQL Server instance 'SQLServer' in database 'WSS_CONTENT'. Additional error information from SQL Server is included below. Could not allocate space for object 'dbo.AllDocStreams'.'AllDocStreams_CI' in database 'mcwane-grp-hsx-content' because the 'PRIMARY' filegroup is full. Create disk space by deleting unneeded files, dropping objects in the filegroup, adding additional files to the filegroup, or setting autogrowth on for existing files in the filegroup.
 

Check if you have enough space on SQL server.

1. Target SQL server data drive is not full
2. .mdf and .ldf files of target content database haven’t reached their full allocated size
3. Target content database files are set to increase when full.

It is recommended to switch database to Simple recovery mode for the time of migration to prevent the database logs from growing and taking space on SQL.