Symptom
When update schema for certain project in 3-tier project source is failed with error “Unknown exception caught(in COM methods)[6]”, while it works in 2-tier.
From engine perf log, it shows the project schema load is finished (like below).
From DFC Engine log, it is updating cube table structure for all the loaded cubes, and it always stop at one certain cube.
Cause
This is because when updating the project schema, it may include changes to the cube structure, such as adding or modifying cube tables, dimensions, or measures. In order for these changes to take effect and be reflected in the cube, it need to reload the cube table structure.
But the reload process stuck as some certain cube that failed to be loaded, which caused the failure for update schema operation.
ACTION
From cube cache monitor, find the next cube after the last successful loaded cube in log, that is the one in issue. Then unload this cube to make the update schema process successful, but it is possible that the process is still failed if there are some other cubes failed to be loaded, use the same way to locate the issued cube and unload.
