How to fix Error 4925 on Windows Server 2025 / Windows 11

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Troubleshooting Guide: Error 4925 – ADD ROWGUIDCOL Failed Due to Existing ROWGUIDCOL Column

Why This Error Happens

This error occurs because SQL Server 2025 enforces a strict rule that only one column per table can carry the ROWGUIDCOL property at any given time. When a user attempts to run ALTER TABLE ALTER COLUMN ADD ROWGUIDCOL on a new or different column, the engine detects that another column already holds this property and blocks the operation to prevent replication and uniqueidentifier conflicts. This is typically not a corruption issue but rather a schema design oversight, often occurring after table migrations, replication setup, or schema merges where the ROWGUIDCOL flag was inadvertently carried over to an unexpected column.

Step-by-Step Resolution Guide

Step 1: Identify the Existing ROWGUIDCOL Column

  • Open SQL Server Management Studio (SSMS) and connect to the target instance.
  • Run the following query to locate the offending column:
SELECT c.name AS ColumnName, t.name AS TableName
FROM sys.columns c
JOIN sys.tables t ON c.object_id = t.object_id
WHERE c.is_rowguidcol = 1 AND t.name = 'YourTableName';
  • Note the column name returned; this is the column currently holding the ROWGUIDCOL property.

Step 2: Remove the ROWGUIDCOL Property from the Existing Column

  • Execute an ALTER TABLE statement to strip the property from the identified column before assigning it elsewhere.
ALTER TABLE YourTableName
ALTER COLUMN ExistingColumnName UNIQUEIDENTIFIER NOT NULL;
  • Note that simply changing the data type definition without the ROWGUIDCOL keyword effectively removes the flag in SQL Server 2025.
  • Verify no replication articles or merge publications are actively referencing this column, as removing the flag mid-replication can cause Error 21046.

Step 3: Apply ROWGUIDCOL to the New Target Column

  • Once the old property is cleared, run the ALTER TABLE command on your intended new column.
ALTER TABLE YourTableName
ALTER COLUMN NewColumnName ADD ROWGUIDCOL;
  • Ensure the column data type is strictly uniqueidentifier; otherwise, the command will fail with a data type mismatch error.

Step 4: Restart the SQL Server Service (If Schema Cache Persists)

  • If the error persists despite the schema change, the metadata cache may need clearing.
  • Open Windows Services (services.msc) on Windows Server 2025.
  • Locate SQL Server (MSSQLSERVER), right-click, and select Restart to force a reload of the table metadata.

Alternative or Verification Steps

  • Run SELECT * FROM sys.columns WHERE is_rowguidcol = 1; filtered by your object_id to confirm only the new column now holds the is_rowguidcol flag set to 1.
  • If the ALTER command continues to fail, drop and recreate the table structure using a SELECT INTO staging approach, manually defining the ROWGUIDCOL property only on the new table during creation to bypass the metadata conflict entirely.