diff --git a/products/warehouse_sources/backend/temporal/data_imports/sources/convex/source.py b/products/warehouse_sources/backend/temporal/data_imports/sources/convex/source.py
index 33d5c7b7a1ba..825aeb922bcf 100644
--- a/products/warehouse_sources/backend/temporal/data_imports/sources/convex/source.py
+++ b/products/warehouse_sources/backend/temporal/data_imports/sources/convex/source.py
@@ -116,6 +116,16 @@ def get_non_retryable_errors(self) -> dict[str, str | None]:
         return {
             "401 Client Error": "Authentication failed. Check your Convex deploy key.",
             "403 Client Error": "Access denied. Check your Convex deploy key.",
+            # A sync only calls list_snapshot / document_deltas, and Convex answers those with a 404
+            # when the table schema discovery listed is gone at read time (deleted on the source, or a
+            # component table that isn't served by streaming export). The next scheduled run reissues
+            # the identical request, so every retry replays the same 404. Cloudflare surfaces transient
+            # edge problems as the 52x/530 family instead (retried in `_CONVEX_RETRY`), so a 404 is
+            # never a transient blip that this could disable a sync over.
+            "404 Client Error": (
+                "PostHog couldn't find this table in your Convex deployment. It was likely deleted, so "
+                "turn off syncing for this table, then re-enable the sync."
+            ),
             "StreamingExportNotEnabled": "Streaming export requires the Convex Professional plan. See https://www.convex.dev/plans to upgrade.",
             # Match a stable substring of the raised message, not the `InvalidWindowError` class name:
             # the non-retryable check compares against `str(exception)`, which contains the message
diff --git a/products/warehouse_sources/backend/temporal/data_imports/sources/convex/tests/test_convex.py b/products/warehouse_sources/backend/temporal/data_imports/sources/convex/tests/test_convex.py
index 564ffeacbc9b..2a8c3f4ffcd8 100644
--- a/products/warehouse_sources/backend/temporal/data_imports/sources/convex/tests/test_convex.py
+++ b/products/warehouse_sources/backend/temporal/data_imports/sources/convex/tests/test_convex.py
@@ -12,6 +12,7 @@
     ReadTimeout,
 )
 
+from products.warehouse_sources.backend.temporal.data_imports.sources.common.base import error_message_matches
 from products.warehouse_sources.backend.temporal.data_imports.sources.common.resumable import ResumableSourceManager
 from products.warehouse_sources.backend.temporal.data_imports.sources.convex.convex import (
     _CONVEX_RETRY,
@@ -558,6 +559,11 @@ def test_get_json_schemas_400_with_unparseable_body_falls_through_to_http_error(
         [
             ("401", "401 Client Error: Unauthorized for url: https://x.convex.cloud/api/document_deltas"),
             ("403", "403 Client Error: Forbidden for url: https://x.convex.cloud/api/document_deltas"),
+            (
+                "missing_table_404",
+                "404 Client Error: Not Found for url: "
+                "https://x.convex.cloud/api/list_snapshot?tableName=verification&format=json&component=betterAuth",
+            ),
             (
                 "invalid_window",
                 "Delta cursor for table 'events' is older than Convex's ~30 day retention window. "
@@ -569,6 +575,24 @@ def test_known_errors_match(self, _name: str, observed_error: str) -> None:
         non_retryable_errors = ConvexSource().get_non_retryable_errors()
         assert any(key in observed_error for key in non_retryable_errors)
 
+    def test_missing_table_404_surfaces_actionable_message(self) -> None:
+        # A deleted table's 404 must stop retrying and tell the customer to turn off syncing for it,
+        # not store the raw driver text (which carries the deployment host). Mirror the finalizer's
+        # first-match selection (external_data_job.py), including its case-insensitive matching via
+        # `error_message_matches`, so a reorder that shadowed it with an earlier None key would be caught.
+        error_msg = (
+            "404 Client Error: Not Found for url: "
+            "https://x.convex.cloud/api/list_snapshot?tableName=verification&format=json&component=betterAuth"
+        )
+        matches = [
+            friendly
+            for key, friendly in ConvexSource().get_non_retryable_errors().items()
+            if error_message_matches(error_msg, [key])
+        ]
+        assert matches, "a missing-table 404 must be classified non-retryable"
+        assert matches[0] is not None, "a missing-table 404 must surface an actionable message, not raw driver text"
+        assert "turn off syncing" in matches[0].lower()
+
     @parameterized.expand(
         [
             ("server_error", "500 Server Error for url: https://x.convex.cloud/api/document_deltas"),