diff --git a/.circleci/config.yml b/.circleci/config.yml
index 8ade1a6296..33331f2770 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -85,7 +85,7 @@ jobs:
           mkdir -p build
           export ENV=ci
           export PROXY_PORT=8080
-          export QUALITY_TIME_VERSION=v5.20.0
+          export QUALITY_TIME_VERSION=v5.21.0-rc.0
           export COMPOSE_PATH_SEPARATOR=':'
           export COMPOSE_FILE=docker/docker-compose.yml:docker/docker-compose.ci.yml
           docker compose build && docker compose up -d
diff --git a/.env b/.env
index 6cb38c973b..1af6822078 100644
--- a/.env
+++ b/.env
@@ -1,4 +1,4 @@
 COMPOSE_PATH_SEPARATOR=:
 COMPOSE_FILE=docker/docker-compose.yml:docker/docker-compose.override.yml
 COMPOSE_PROJECT_NAME=quality-time
-QUALITY_TIME_VERSION=v5.20.0
+QUALITY_TIME_VERSION=v5.21.0-rc.0
diff --git a/.github/workflows/application-tests.yml b/.github/workflows/application-tests.yml
index 48b24e5c12..3540c7841b 100644
--- a/.github/workflows/application-tests.yml
+++ b/.github/workflows/application-tests.yml
@@ -16,7 +16,7 @@ jobs:
           password: ${{ secrets.DOCKER_PASSWORD }}
       - name: Run application tests
         env:
-          QUALITY_TIME_VERSION: v5.20.0
+          QUALITY_TIME_VERSION: v5.21.0-rc.0
           ENV: ci
           PROXY_PORT: 8080
         run: |
diff --git a/components/api_server/pyproject.toml b/components/api_server/pyproject.toml
index 8e53a30b0c..2b236e0f73 100644
--- a/components/api_server/pyproject.toml
+++ b/components/api_server/pyproject.toml
@@ -1,6 +1,6 @@
 [project]
 name = "api-server"
-version = "5.20.0"
+version = "5.21.0-rc.0"
 requires-python = ">=3.13"
 classifiers = [
     "Programming Language :: Python :: 3 :: Only",
diff --git a/components/api_server/src/routes/server.py b/components/api_server/src/routes/server.py
index ed41f5822a..dfe49dde11 100644
--- a/components/api_server/src/routes/server.py
+++ b/components/api_server/src/routes/server.py
@@ -3,7 +3,7 @@
 import bottle
 
 
-QUALITY_TIME_VERSION = "5.20.0"
+QUALITY_TIME_VERSION = "5.21.0-rc.0"
 
 
 @bottle.get("/api/v3/server", authentication_required=False)
diff --git a/components/collector/pyproject.toml b/components/collector/pyproject.toml
index dda72cd859..576aebf3e2 100644
--- a/components/collector/pyproject.toml
+++ b/components/collector/pyproject.toml
@@ -1,6 +1,6 @@
 [project]
 name = "collector"
-version = "5.20.0"
+version = "5.21.0-rc.0"
 requires-python = ">=3.13"
 classifiers = [
     "Programming Language :: Python :: 3 :: Only",
diff --git a/components/frontend/package.json b/components/frontend/package.json
index 0f491e99a9..0cc7e9e519 100644
--- a/components/frontend/package.json
+++ b/components/frontend/package.json
@@ -1,6 +1,6 @@
 {
     "name": "quality-time-app",
-    "version": "5.20.0",
+    "version": "5.21.0-rc.0",
     "private": true,
     "proxy": "http://127.0.0.1:5001",
     "dependencies": {
diff --git a/components/notifier/pyproject.toml b/components/notifier/pyproject.toml
index 5711dc0e5f..e30e47b309 100644
--- a/components/notifier/pyproject.toml
+++ b/components/notifier/pyproject.toml
@@ -1,6 +1,6 @@
 [project]
 name = "notifier"
-version = "5.20.0"
+version = "5.21.0-rc.0"
 requires-python = ">=3.13"
 classifiers = [
     "Programming Language :: Python :: 3 :: Only",
diff --git a/components/renderer/package.json b/components/renderer/package.json
index e36f808902..16f45824d8 100644
--- a/components/renderer/package.json
+++ b/components/renderer/package.json
@@ -1,6 +1,6 @@
 {
     "name": "quality-time-renderer",
-    "version": "5.20.0",
+    "version": "5.21.0-rc.0",
     "private": true,
     "type": "module",
     "proxy": "http://localhost:9000",
diff --git a/components/shared_code/pyproject.toml b/components/shared_code/pyproject.toml
index 69fd3cd070..e07a6d794d 100644
--- a/components/shared_code/pyproject.toml
+++ b/components/shared_code/pyproject.toml
@@ -1,6 +1,6 @@
 [project]
 name = "shared-code"
-version = "5.20.0"
+version = "5.21.0-rc.0"
 requires-python = ">=3.13"
 classifiers = [
     "Programming Language :: Python :: 3 :: Only",
diff --git a/docs/pyproject.toml b/docs/pyproject.toml
index 2bf9f387fa..ef17ebada8 100644
--- a/docs/pyproject.toml
+++ b/docs/pyproject.toml
@@ -1,6 +1,6 @@
 [project]
 name = "docs"
-version = "5.20.0"
+version = "5.21.0-rc.0"
 requires-python = ">=3.13"
 classifiers = [
     "Programming Language :: Python :: 3 :: Only",
diff --git a/helm/Chart.yaml b/helm/Chart.yaml
index 654d13a2a2..b256c992ad 100644
--- a/helm/Chart.yaml
+++ b/helm/Chart.yaml
@@ -1,8 +1,8 @@
 ---
 apiVersion: v2
 name: quality-time
-version: 5.20.0
-appVersion: "v5.20.0"
+version: 5.21.0-rc.0
+appVersion: "v5.21.0-rc.0"
 description: Helm chart for Quality-time, an automated quality system for software development and maintenance
 type: application
 home: https://github.com/ICTU/Quality-time
diff --git a/release/pyproject.toml b/release/pyproject.toml
index daeedceef6..4104200d9c 100644
--- a/release/pyproject.toml
+++ b/release/pyproject.toml
@@ -1,6 +1,6 @@
 [project]
 name = "release"
-version = "5.20.0"
+version = "5.21.0-rc.0"
 requires-python = ">=3.13"
 classifiers = [
     "Programming Language :: Python :: 3 :: Only",
@@ -43,7 +43,7 @@ indent = 4
 keep_full_version = true # Don't remove trailing zero's from version specifiers
 
 [tool.bumpversion]
-current_version = "5.20.0"
+current_version = "5.21.0-rc.0"
 parse = """(?x)
     (?P<major>0|[1-9]\\d*)\\.
     (?P<minor>0|[1-9]\\d*)\\.
diff --git a/sonar-project.properties b/sonar-project.properties
index ecd7dbc2ba..d769550226 100644
--- a/sonar-project.properties
+++ b/sonar-project.properties
@@ -2,7 +2,7 @@
 sonar.organization=ictu
 sonar.projectKey=nl.ictu:quality-time
 sonar.projectName=Quality-time
-sonar.projectVersion=5.20.0
+sonar.projectVersion=5.21.0-rc.0
 
 # Path is relative to the sonar-project.properties file. Replace "\" by "/" on Windows.
 # This property is optional if sonar.modules is set.
diff --git a/tests/application_tests/pyproject.toml b/tests/application_tests/pyproject.toml
index 9244ccafa8..901075b0f2 100644
--- a/tests/application_tests/pyproject.toml
+++ b/tests/application_tests/pyproject.toml
@@ -1,6 +1,6 @@
 [project]
 name = "application-tests"
-version = "5.20.0"
+version = "5.21.0-rc.0"
 requires-python = ">=3.13"
 classifiers = [
     "Programming Language :: Python :: 3 :: Only",
diff --git a/tests/feature_tests/pyproject.toml b/tests/feature_tests/pyproject.toml
index 1114bbe3bd..71f74b6edf 100644
--- a/tests/feature_tests/pyproject.toml
+++ b/tests/feature_tests/pyproject.toml
@@ -1,6 +1,6 @@
 [project]
 name = "feature-tests"
-version = "5.20.0"
+version = "5.21.0-rc.0"
 requires-python = ">=3.13"
 classifiers = [
     "Programming Language :: Python :: 3 :: Only",