PRB: Merge Replication Fails with "Process could not enumerate changes" Error Message When Assigning a Blank Value to an Image Column (280684)

SYMPTOMS

When you assign a blank value to an image column table that is part of merge replication, the Merge agent may fail with the following error message:

The process could not enumerate changes at the Subscriber.

Full Message: Invalid argument value

This behavior only happens when the image column is updated to an empty string value such as "" on either the Publishing or Subscribing merge table.

You can check whether you have an empty string value in your image column by viewing the binary value stored in the image column. A binary value of "0x" indicates an empty string value.

CAUSE

This error message occurs because of an incorrect data conversion by the SQLGetData ODBC driver function. The SQLGetData function incorrectly interprets a blank value stored in the image column.

WORKAROUND

Avoid assigning empty string values ("") to the image columns.

To resolve this merge agent error, UPDATE the image column to a non-empty string value such as NULL or to an actual string value.

MORE INFORMATION

Steps to Reproduce Problem

Run the following CREATE TABLE statement:

Create Table Imagetest1 (c1 int ,c2 image,c3 char(4), c4
uniqueidentifier rowguidcol)

Publish the table for Merge Replication.
Run the following INSERT statement, which updates the image column to a blank value.
```
   Insert Imagetest1 values(1,'','merge_test',newid())
					
```
Run the Merge agent. The Merge agent fails because of an invalid data type conversion for the image column.
To resolve this error, run the following UPDATE statement:
```
UPDATE Imagetest1 set image = 'non_blank_value' where c1 = 1
					
```
The Merge agent now runs successfully.