diff --git a/components/api_server/src/initialization/migrations.py b/components/api_server/src/initialization/migrations.py
index 8373cd744d..0f3274df28 100644
--- a/components/api_server/src/initialization/migrations.py
+++ b/components/api_server/src/initialization/migrations.py
@@ -19,6 +19,7 @@ def perform_migrations(database: Database) -> None:
             changes := [
                 change_accessibility_violation_metrics_to_violations(report),
                 fix_branch_parameters_without_value(report),
+                remove_test_cases_manual_number(report),
                 change_ci_subject_types_to_development_environment(report),
                 change_sonarqube_parameters(report),
             ]
@@ -59,6 +60,18 @@ def fix_branch_parameters_without_value(report) -> str:
     return change
 
 
+def remove_test_cases_manual_number(report) -> str:
+    """Remove manual number sources from test cases metrics."""
+    # Added after Quality-time v5.15.0, see https://github.com/ICTU/quality-time/issues/9793
+    change = ""
+    for metric in metrics(report, metric_types=("test_cases",)):
+        for source_uuid, source in metric.get("sources", {}).copy().items():
+            if source["type"] == "manual_number":
+                del metric["sources"][source_uuid]
+                change = "remove manual number sources from test cases metrics"
+    return change
+
+
 METRICS_WITH_SOURCES_WITH_BRANCH_PARAMETER = {
     "commented_out_code": ["sonarqube"],
     "complex_units": ["sonarqube"],
diff --git a/components/api_server/tests/initialization/test_migrations.py b/components/api_server/tests/initialization/test_migrations.py
index d7657848bc..c4fa36008e 100644
--- a/components/api_server/tests/initialization/test_migrations.py
+++ b/components/api_server/tests/initialization/test_migrations.py
@@ -1,5 +1,7 @@
 """Unit tests for database migrations."""
 
+from collections.abc import Mapping
+
 from initialization.migrations import perform_migrations
 
 from tests.base import DataModelTestCase, disable_logging
@@ -15,7 +17,7 @@ def existing_report(
         metric_type: str,
         metric_name: str = "",
         metric_unit: str = "",
-        sources: dict[SourceId, dict[str, str | dict[str, str]]] | None = None,
+        sources: Mapping[SourceId, Mapping[str, str | Mapping[str, str]]] | None = None,
     ):
         """Return a report fixture. To be extended in subclasses."""
         report: dict = {
@@ -27,7 +29,7 @@ def existing_report(
             report["subjects"][SUBJECT_ID]["metrics"][METRIC_ID]["name"] = metric_name
         if metric_unit:
             report["subjects"][SUBJECT_ID]["metrics"][METRIC_ID]["unit"] = metric_unit
-        if sources:
+        if sources is not None:
             report["subjects"][SUBJECT_ID]["metrics"][METRIC_ID]["sources"] = sources
         return report
 
@@ -308,3 +310,44 @@ def test_report_with_security_types_parameter_without_values(self):
         self.database.reports.find.return_value = reports
         perform_migrations(self.database)
         self.database.reports.replace_one.assert_not_called()
+
+
+class TestCasesManualNumberTest(MigrationTestCase):
+    """Unit tests for the test cases manual number source migration."""
+
+    def sources(self, source_type: str = "manual_number", source_type2: str = ""):
+        """Create the sources fixture."""
+        sources = {SOURCE_ID: {"type": source_type}}
+        if source_type2:
+            sources[SOURCE_ID2] = {"type": source_type2}
+        return sources
+
+    def test_report_with_test_cases_and_jira_source(self):
+        """Test that the other sources are not removed."""
+        self.database.reports.find.return_value = [
+            self.existing_report(metric_type="test_cases", sources=self.sources("jira")),
+        ]
+        perform_migrations(self.database)
+        self.database.reports.replace_one.assert_not_called()
+
+    def test_report_with_test_cases_and_manual_number_source(self):
+        """Test that the manual number source is removed."""
+        self.database.reports.find.return_value = [
+            self.existing_report(metric_type="test_cases", sources=self.sources()),
+        ]
+        perform_migrations(self.database)
+        self.database.reports.replace_one.assert_called_once_with(
+            {"_id": "id"},
+            self.inserted_report(metric_type="test_cases", sources={}),
+        )
+
+    def test_report_with_test_cases_and_jira_and_manual_number_source(self):
+        """Test that the manual number source is removed."""
+        self.database.reports.find.return_value = [
+            self.existing_report(metric_type="test_cases", sources=self.sources("jira", "manual_number")),
+        ]
+        perform_migrations(self.database)
+        self.database.reports.replace_one.assert_called_once_with(
+            {"_id": "id"},
+            self.inserted_report(metric_type="test_cases", sources=self.sources("jira")),
+        )
diff --git a/components/shared_code/src/shared_data_model/metrics.py b/components/shared_code/src/shared_data_model/metrics.py
index a65ee20a88..0bec031297 100644
--- a/components/shared_code/src/shared_data_model/metrics.py
+++ b/components/shared_code/src/shared_data_model/metrics.py
@@ -576,7 +576,7 @@
         unit=Unit.TEST_CASES,
         direction=Direction.MORE_IS_BETTER,
         near_target="0",
-        sources=["jenkins_test_report", "jira", "junit", "manual_number", "robot_framework", "testng"],
+        sources=["jenkins_test_report", "jira", "junit", "robot_framework", "testng"],
         tags=[Tag.TEST_QUALITY],
     ),
     "tests": Metric(
diff --git a/components/shared_code/src/shared_data_model/sources/manual_number.py b/components/shared_code/src/shared_data_model/sources/manual_number.py
index 451129714a..173d787dee 100644
--- a/components/shared_code/src/shared_data_model/sources/manual_number.py
+++ b/components/shared_code/src/shared_data_model/sources/manual_number.py
@@ -45,7 +45,6 @@
                 "sentiment",
                 "slow_transactions",
                 "suppressed_violations",
-                "test_cases",
                 "tests",
                 "todo_and_fixme_comments",
                 "uncovered_branches",
diff --git a/docs/src/changelog.md b/docs/src/changelog.md
index 70c52903bf..c239234b84 100644
--- a/docs/src/changelog.md
+++ b/docs/src/changelog.md
@@ -33,6 +33,10 @@ If your currently installed *Quality-time* version is not v5.15.0, please first
 
 - Start replacing Semantic UI React with Material UI as frontend component library. This migration will probably span multiple releases. Until the migration is finished, the UI may contain inconsistent elements, such as fonts, colors, and icons. Closes [#9550](https://github.com/ICTU/quality-time/issues/9550).
 
+### Removed
+
+- The 'test cases' metric had 'manual number' as supported source for the metric, but that could never work since the metric needs sources that contain test cases with identifiers so they can be matched. Manual number sources for test cases metrics are removed from reports automatically on application startup. Fixes [#9793](https://github.com/ICTU/quality-time/issues/9793).
+
 ## v5.15.0 - 2024-07-30
 
 ### Deployment notes
diff --git a/docs/src/versioning.md b/docs/src/versioning.md
index d4e15d6794..cd2e978f34 100644
--- a/docs/src/versioning.md
+++ b/docs/src/versioning.md
@@ -19,27 +19,28 @@ A new **patch** release of *Quality-time* is made when the new version has only
 
 The table below contains the *Quality-time* releases since the last minor of the previous major release. For each release it shows the release date, the MongoDB version included, the MongoDB feature compatibility (FC) version set in the database, whether migration code was added or removed, and whether up- or downgrading is possible, and if so, to which versions.
 
-| Version    | Date         | Mongo  | FC     | Migrations | Downgrade      | Upgrade         |
-|------------|--------------|--------|--------|------------|----------------|-----------------|
-| v5.15.0    | 2024-07-30   | v7     | v7     |            | v5.14.0        | n/a             |
-| v5.14.0    | 2024-07-05   | v7     | **v7** | added      | not possible   | v5.15.0         |
-| v5.13.0    | 2024-05-23   | v7     | v6     | added      | not possible   | v5.14.0-v5.15.0 |
-| v5.12.0    | 2024-05-17   | v7     | v6     | added      | not possible   | v5.13.0-v5.15.0 |
-| v5.11.0    | 2024-04-22   | v7     | v6     |            | v5.6.0-v5.10.0 | v5.12.0-v5.15.0 |
-| v5.10.0    | 2024-04-15   | v7     | v6     |            | v5.6.0-v5.9.0  | v5.11.0-v5.15.0 |
-| v5.9.0     | 2024-03-22   | v7     | v6     |            | v5.6.0-v5.8.0  | v5.10.0-v5.15.0 |
-| v5.8.0     | 2024-02-16   | v7     | v6     |            | v5.6.0-v5.7.0  | v5.9.0-v5.15.0  |
-| v5.7.0     | 2024-01-31   | v7     | v6     |            | v5.6.0         | v5.8.0-v5.15.0  |
-| v5.6.0     | 2024-01-12   | v7     | v6     | added      | not possible   | v5.7.0-v5.15.0  |
-| v5.5.0     | 2023-12-15   | v7     | v6     |            | v5.1.0-v5.4.0  | v5.6.0-v5.15.0  |
-| v5.4.0     | 2023-12-11   | v7     | v6     |            | v5.1.0-v5.3.1  | v5.5.0-v5.15.0  |
-| v5.3.1     | 2023-11-08   | v7     | v6     |            | v5.1.0-v5.3.0  | v5.4.0-v5.15.0  |
-| v5.3.0     | 2023-11-07   | **v7** | v6     |            | v5.1.0-v5.2.0  | v5.3.1-v5.15.0  |
-| v5.2.0     | 2023-09-29   | v6     | v6     |            | v5.1.0         | v5.3.0-v5.15.0  |
-| v5.1.0     | 2023-09-05   | v6     | **v6** |            | not possible   | v5.2.0-v5.15.0  |
-| v5.0.1     | 2023-06-26   | v6     | v5     |            | v4.10.0-v5.0.0 | v5.1.0-v5.2.0   |
-| **v5.0.0** | 2023-06-23   | **v6** | v5     |            | v4.10.0        | v5.0.1-v5.2.0   |
-| v4.10.0    | 2023-04-26   | v5     | v5     |            | n/a            | v5.0.0-v5.2.0   |
+| Version    | Date         | Mongo  | FC     | Migrations | Downgrade       | Upgrade         |
+|------------|--------------|--------|--------|------------|-----------------|-----------------|
+| v5.16.0    | [unreleased] | v7     | v7     | added      | v5.14.0-v5.15.0 | n/a             |
+| v5.15.0    | 2024-07-30   | v7     | v7     |            | v5.14.0         | v5.16.0         |
+| v5.14.0    | 2024-07-05   | v7     | **v7** | added      | not possible    | v5.15.0-v5.16.0 |
+| v5.13.0    | 2024-05-23   | v7     | v6     | added      | not possible    | v5.14.0-v5.16.0 |
+| v5.12.0    | 2024-05-17   | v7     | v6     | added      | not possible    | v5.13.0-v5.16.0 |
+| v5.11.0    | 2024-04-22   | v7     | v6     |            | v5.6.0-v5.10.0  | v5.12.0-v5.16.0 |
+| v5.10.0    | 2024-04-15   | v7     | v6     |            | v5.6.0-v5.9.0   | v5.11.0-v5.16.0 |
+| v5.9.0     | 2024-03-22   | v7     | v6     |            | v5.6.0-v5.8.0   | v5.10.0-v5.16.0 |
+| v5.8.0     | 2024-02-16   | v7     | v6     |            | v5.6.0-v5.7.0   | v5.9.0-v5.16.0  |
+| v5.7.0     | 2024-01-31   | v7     | v6     |            | v5.6.0          | v5.8.0-v5.16.0  |
+| v5.6.0     | 2024-01-12   | v7     | v6     | added      | not possible    | v5.7.0-v5.16.0  |
+| v5.5.0     | 2023-12-15   | v7     | v6     |            | v5.1.0-v5.4.0   | v5.6.0-v5.16.0  |
+| v5.4.0     | 2023-12-11   | v7     | v6     |            | v5.1.0-v5.3.1   | v5.5.0-v5.16.0  |
+| v5.3.1     | 2023-11-08   | v7     | v6     |            | v5.1.0-v5.3.0   | v5.4.0-v5.16.0  |
+| v5.3.0     | 2023-11-07   | **v7** | v6     |            | v5.1.0-v5.2.0   | v5.3.1-v5.16.0  |
+| v5.2.0     | 2023-09-29   | v6     | v6     |            | v5.1.0          | v5.3.0-v5.16.0  |
+| v5.1.0     | 2023-09-05   | v6     | **v6** |            | not possible    | v5.2.0-v5.16.0  |
+| v5.0.1     | 2023-06-26   | v6     | v5     |            | v4.10.0-v5.0.0  | v5.1.0-v5.2.0   |
+| **v5.0.0** | 2023-06-23   | **v6** | v5     |            | v4.10.0         | v5.0.1-v5.2.0   |
+| v4.10.0    | 2023-04-26   | v5     | v5     |            | n/a             | v5.0.0-v5.2.0   |
 
 ## Upgrade path