​​​​Value for Column 'X' was Sent to the Data Source but Value '' was Returned

Error Example:

Not a true error, but a metabase recovery message in debug.

The metabase record '5deecddd-0818-47bf-9689-799d98c57db0' is marked to be updated. The row '<rowIdentifier>' is marked with the error 'The value '<dataValue>' for column '<columnsName>' was sent to the data source, but value '' was returned.'. Changes made to this metabase record will be reset to the initial state.

Cause:

As noted above, this is not an error per se, but a debug message about metabase recovery due to a data issue. This message is noting a safeguard to prevent unexpected values in the metabase. There should be an actual error further up the log that explains what the issue was.

Example Case:

When the Connector writes a value like "0" to a data-entity, it will read the value back and save the read-back value as the current value in the entity. So that if the entity formats the value like "0.00" we will have a metabase entry that says "The value 0 on the left is the same as 0.00 on the right".

If, however, there was some kind of error and the value has not been written at all, the Connector would think "The value 0 on the left is the same as nothing on the right". This has been leading to situations where, even the error cause itself has been fixed, the Connector would never update the column without metabase-deletion.

To prevent that, we implemented this safeguard, which actually works on the premise that "Something can't be nothing", so that whenever the Connectorwrote something to an entity and the readback returned nothing, it will throw an error which causes the metabase to be reset for this record.

Resolution/Workaround:

You can review the log files to identify the actual error that usually happens during the sync. In most cases, there should be a data issue listed (lookup didn't match, wrong data type, string over length limit for field, wrong decimal format, etc.) However for SharePoint, it can sometimes fail silently (SharePoint will ignore the data problem and not throw an error). It should still be a data type issue, so check the value being entered (listed in the debug log) into the column (also listed in the debug log) for data issues.

Another common issue are values coming from SQL that are spaces (one or more spaces or non-visible characters). SharePoint will truncate these to a true blank (as that is what it thinks the user intended as there's no data), leading to this error. For these cases, you need to update you database values to be true blank (not a space) or NULL to clear the error. You can also use Dynamic Columns to fix this at run time if the spaces come from another system the data base is attached to.​

if (myField.Trim().Length == 0)
{
return myField.Trim();
}
else
{
return myField​;
}

Then map this Dynamic Column instead of the original field.