Solution or Workaround
Trying to reconnect to an SDE for Informix Database using a saved ArcView 3.x project may produce an error. As you try to open a project that includes such a connection, you may see a pop-up message stating "Database instance not connected".
If you look in the file SDEHOME/etc/sde.errlog on the SDE for Informix server, you will see a message similar to this one:
SDE_Database Error: -1
IM002
ODBC Error: IM002
Database Error: -11041
Error Message: [Informix][Odbc Informix Driver]Data source name not found and no default driver specified.
CAN'T OPEN INSTANCE: sde5152.
Spatial Engine Connection Failed (-158).
Cannot Get Access to Instance
Cause:
The ArcView 3.1 and 3.2 project does not properly save the name of the database that contains the layer.
Solution:
There is no current solution. This is a known limit.