I'm trying to export feature classes (tested shapefile too) to DGN and I keep receiving this error. I've tried exporting a smaller subset of features, moving them to a different database, and exporting as DWG. I've also tried checking and repairing geometry (there weren't any).
Error: ERROR 000520: Unexpected TopoEngine Error
Did you create a featureclass in a locally stored file geodatabase as the source file? It sometimes corrects geometry and/or topology issues.
Yes all the data is local.
Esri Technical Support - Error: 000520 : Unexpected TopoEngine Error (esri.com)
000520: Unexpected TopoEngine Error.—ArcGIS Pro | Documentation
if still encounter issues then open a ticket with Esri Technical Support to investigate.