diff --git a/mp_api/client/core/client.py b/mp_api/client/core/client.py
index 1e2488d5..2b553045 100644
--- a/mp_api/client/core/client.py
+++ b/mp_api/client/core/client.py
@@ -5,6 +5,7 @@
 
 from __future__ import annotations
 
+import inspect
 import itertools
 import json
 import os
@@ -419,7 +420,7 @@ def _query_resource(
         """Query the endpoint for a Resource containing a list of documents
         and meta information about pagination and total document count.
 
-        For the end-user, methods .query() and .count() are intended to be
+        For the end-user, methods .search() and .count() are intended to be
         easier to use.
 
         Arguments:
@@ -994,8 +995,9 @@ def _submit_request_and_process(
             )
 
         if response.status_code in [400]:
-            warnings.warn(
-                f"The server does not support the request made to {response.url}. This may be due to an outdated mp-api package, or a problem with the query."
+            raise MPRestError(
+                f"The server does not support the request made to {response.url}. "
+                "This may be due to an outdated mp-api package, or a problem with the query."
             )
 
         if response.status_code == 200:
@@ -1266,34 +1268,45 @@ def count(self, criteria: dict | None = None) -> int | str:
         """Return a count of total documents.
 
         Args:
-            criteria (dict | None): As in .query(). Defaults to None
+            criteria (dict | None): As in .search(). Defaults to None
 
         Returns:
             (int | str): Count of total results, or string indicating error
         """
-        try:
-            criteria = criteria or {}
-            user_preferences = (
-                self.monty_decode,
-                self.use_document_model,
-                self.mute_progress_bars,
-            )
-            self.monty_decode, self.use_document_model, self.mute_progress_bars = (
-                False,
-                False,
-                True,
-            )  # do not waste cycles decoding
-            results = self._query_resource(
-                criteria=criteria, num_chunks=1, chunk_size=1
-            )
-            (
-                self.monty_decode,
-                self.use_document_model,
-                self.mute_progress_bars,
-            ) = user_preferences
-            return results["meta"]["total_doc"]
-        except Exception:  # pragma: no cover
-            return "Problem getting count"
+        criteria = criteria or {}
+        user_preferences = (
+            self.monty_decode,
+            self.use_document_model,
+            self.mute_progress_bars,
+        )
+        self.monty_decode, self.use_document_model, self.mute_progress_bars = (
+            False,
+            False,
+            True,
+        )  # do not waste cycles decoding
+        results = self._query_resource(criteria=criteria, num_chunks=1, chunk_size=1)
+        cnt = results["meta"]["total_doc"]
+
+        no_query = not {field for field in criteria if field[0] != "_"}
+        if no_query and hasattr(self, "search"):
+            allowed_params = inspect.getfullargspec(self.search).args
+            if "deprecated" in allowed_params:
+                criteria["deprecated"] = True
+                results = self._query_resource(
+                    criteria=criteria, num_chunks=1, chunk_size=1
+                )
+                cnt += results["meta"]["total_doc"]
+                warnings.warn(
+                    "Omitting a query also includes deprecated documents in the results. "
+                    "Make sure to post-filter them out."
+                )
+
+        (
+            self.monty_decode,
+            self.use_document_model,
+            self.mute_progress_bars,
+        ) = user_preferences
+        return cnt
 
     @property
     def available_fields(self) -> list[str]: