diff --git a/plugins/printers/api/asset_routes.py b/plugins/printers/api/asset_routes.py
index e626b95e..e2bed15a 100644
--- a/plugins/printers/api/asset_routes.py
+++ b/plugins/printers/api/asset_routes.py
@@ -1123,12 +1123,18 @@ def set_asset_printer_assignment(asset_id: int):
                     ', '.join(str(assetid) for assetid in sorted(notprinters))))
 
     typeids = _relationship_typeids(_USES_PRINTER, _DEFAULT_PRINTER)
-    if not typeids[_USES_PRINTER] or not typeids[_DEFAULT_PRINTER]:
+    missingtypes = [name for name in (_USES_PRINTER, _DEFAULT_PRINTER)
+                    if not typeids[name]]
+    if missingtypes:
         # Seed data, not a migration. An un-seeded database cannot hold an
-        # assignment, and saying so beats writing rows nothing can read.
+        # assignment, and saying so beats writing rows nothing can read. Name
+        # the types that are actually missing: a partially seeded table is the
+        # common case, and "types are not seeded" sends someone looking for an
+        # empty table they will not find.
         return error_response(
             ErrorCodes.INTERNAL_ERROR,
-            'Relationship types are not seeded - run: flask seed reference-data',
+            'Relationship type(s) not seeded: {0} - run: flask seed '
+            'reference-data'.format(', '.join(missingtypes)),
             http_code=500)
 
     _reconcile_edges(asset_id, typeids[_USES_PRINTER][0],
@@ -1784,10 +1790,13 @@ def seed_assignment_from_observed(asset_id: int):
             details={'hostname': hostname, 'skipped': candidate['skipped']})
 
     typeids = _relationship_typeids(_USES_PRINTER, _DEFAULT_PRINTER, _CONTROLS)
-    if not typeids[_USES_PRINTER] or not typeids[_DEFAULT_PRINTER]:
+    missingtypes = [name for name in (_USES_PRINTER, _DEFAULT_PRINTER)
+                    if not typeids[name]]
+    if missingtypes:
         return error_response(
             ErrorCodes.INTERNAL_ERROR,
-            'Relationship types are not seeded - run: flask seed reference-data',
+            'Relationship type(s) not seeded: {0} - run: flask seed '
+            'reference-data'.format(', '.join(missingtypes)),
             http_code=500)
 
     warnings = []