diff --git a/.changeset/unlucky-snakes-turn.md b/.changeset/unlucky-snakes-turn.md
new file mode 100644
index 0000000000..bcb31feb40
--- /dev/null
+++ b/.changeset/unlucky-snakes-turn.md
@@ -0,0 +1,5 @@
+---
+'@backstage/plugin-jenkins-backend': patch
+---
+
+Fixed possible type error if jenkins response contains null values
diff --git a/plugins/jenkins-backend/src/service/jenkinsApi.test.ts b/plugins/jenkins-backend/src/service/jenkinsApi.test.ts
index bc7d2cb029..1d72dbf71c 100644
--- a/plugins/jenkins-backend/src/service/jenkinsApi.test.ts
+++ b/plugins/jenkins-backend/src/service/jenkinsApi.test.ts
@@ -352,6 +352,216 @@ describe('JenkinsApi', () => {
 
         const result = await jenkinsApi.getProjects(jenkinsInfo);
 
+        expect(result).toHaveLength(1);
+        expect(result[0].lastBuild!.tests).toEqual({
+          total: 635,
+          passed: 632,
+          skipped: 1,
+          failed: 2,
+          testUrl:
+            'https://jenkins.example.com/job/example-jobName/job/exampleBuild/7/testReport/',
+        });
+      });
+    });
+    describe('augmented with null values', () => {
+      const projectWithScmActionsAndNulls: JenkinsProject = {
+        actions: [
+          {},
+          {},
+          null,
+          {},
+          {
+            _class: 'jenkins.scm.api.metadata.ContributorMetadataAction',
+            contributor: 'testuser',
+            contributorDisplayName: 'Mr. T User',
+            contributorEmail: null,
+          },
+          {},
+          {
+            _class: 'jenkins.scm.api.metadata.ObjectMetadataAction',
+            objectDescription: '',
+            objectDisplayName: 'Add LICENSE, CoC etc',
+            objectUrl: 'https://github.com/backstage/backstage/pull/1',
+          },
+          {},
+          {},
+          {
+            _class: 'com.cloudbees.plugins.credentials.ViewCredentialsAction',
+            stores: {},
+          },
+        ],
+        displayName: 'Example Build',
+        fullDisplayName: 'Example jobName » Example Build',
+        fullName: 'example-jobName/exampleBuild',
+        inQueue: false,
+        lastBuild: {
+          actions: [
+            {
+              _class: 'hudson.model.CauseAction',
+              causes: [
+                {
+                  _class: 'jenkins.branch.BranchIndexingCause',
+                  shortDescription: 'Branch indexing',
+                },
+              ],
+            },
+            null,
+            {},
+            {},
+            {
+              _class: 'org.jenkinsci.plugins.workflow.cps.EnvActionImpl',
+              environment: {},
+            },
+            {},
+            {},
+            {},
+            {},
+            {},
+            {
+              _class: 'hudson.plugins.git.util.BuildData',
+              buildsByBranchName: {
+                'PR-1': {
+                  _class: 'hudson.plugins.git.util.Build',
+                  buildNumber: 5,
+                  buildResult: null,
+                  marked: {
+                    SHA1: '14d31bde346fcad64ab939f82d195db36701cfcb',
+                    branch: [
+                      {
+                        SHA1: '14d31bde346fcad64ab939f82d195db36701cfcb',
+                        name: 'PR-1',
+                      },
+                    ],
+                  },
+                  revision: {
+                    SHA1: '6c6b34c0fb91cf077a01fe62d3e8e996b4ea5861',
+                    branch: [
+                      {
+                        SHA1: '14d31bde346fcad64ab939f82d195db36701cfcb',
+                        name: 'PR-1',
+                      },
+                    ],
+                  },
+                },
+              },
+              lastBuiltRevision: {
+                SHA1: '6c6b34c0fb91cf077a01fe62d3e8e996b4ea5861',
+                branch: [
+                  {
+                    SHA1: '14d31bde346fcad64ab939f82d195db36701cfcb',
+                    name: 'PR-1',
+                  },
+                ],
+              },
+              remoteUrls: ['https://github.com/backstage/backstage.git'],
+              scmName: '',
+            },
+            {
+              _class: 'hudson.plugins.git.util.BuildData',
+              buildsByBranchName: {
+                master: {
+                  _class: 'hudson.plugins.git.util.Build',
+                  buildNumber: 5,
+                  buildResult: null,
+                  marked: {
+                    SHA1: '14d31bde346fcad64ab939f82d195db36701cfcb',
+                    branch: [
+                      {
+                        SHA1: '14d31bde346fcad64ab939f82d195db36701cfcb',
+                        name: 'master',
+                      },
+                    ],
+                  },
+                  revision: {
+                    SHA1: '6c6b34c0fb91cf077a01fe62d3e8e996b4ea5861',
+                    branch: [
+                      {
+                        SHA1: '14d31bde346fcad64ab939f82d195db36701cfcb',
+                        name: 'master',
+                      },
+                    ],
+                  },
+                },
+              },
+              lastBuiltRevision: {
+                SHA1: '6c6b34c0fb91cf077a01fe62d3e8e996b4ea5861',
+                branch: [
+                  {
+                    SHA1: '14d31bde346fcad64ab939f82d195db36701cfcb',
+                    name: 'master',
+                  },
+                ],
+              },
+              remoteUrls: ['https://github.com/backstage/backstage.git'],
+              scmName: '',
+            },
+            {},
+            {},
+            {
+              _class: 'hudson.tasks.junit.TestResultAction',
+              failCount: 2,
+              skipCount: 1,
+              totalCount: 635,
+              urlName: 'testReport',
+            },
+            {},
+            {},
+            {
+              _class:
+                'org.jenkinsci.plugins.pipeline.modeldefinition.actions.RestartDeclarativePipelineAction',
+              restartEnabled: false,
+              restartableStages: [],
+            },
+            {},
+          ],
+          timestamp: 1,
+          building: false,
+          duration: 10,
+          result: 'success',
+          displayName: '#7',
+          fullDisplayName: 'Example jobName » Example Build #7',
+          url: 'https://jenkins.example.com/job/example-jobName/job/exampleBuild/7/',
+          number: 7,
+        },
+      };
+
+      it('augments project', async () => {
+        mockedJenkinsClient.job.get.mockResolvedValueOnce({
+          jobs: [projectWithScmActionsAndNulls],
+        });
+
+        const result = await jenkinsApi.getProjects(jenkinsInfo);
+
+        expect(result).toHaveLength(1);
+        expect(result[0].status).toEqual('success');
+      });
+      it('augments  build', async () => {
+        mockedJenkinsClient.job.get.mockResolvedValueOnce({
+          jobs: [projectWithScmActionsAndNulls],
+        });
+
+        const result = await jenkinsApi.getProjects(jenkinsInfo);
+
+        expect(result).toHaveLength(1);
+        // TODO: I am really just asserting the previous behaviour with no understanding here.
+        // In my 2 Jenkins instances, 1 returns a lot of different and confusing BuildData sections and 1 returns none ☹️
+        expect(result[0].lastBuild!.source).toEqual({
+          branchName: 'master',
+          commit: {
+            hash: '14d31bde',
+          },
+          url: 'https://github.com/backstage/backstage/pull/1',
+          displayName: 'Add LICENSE, CoC etc',
+          author: 'Mr. T User',
+        });
+      });
+      it('finds test report', async () => {
+        mockedJenkinsClient.job.get.mockResolvedValueOnce({
+          jobs: [projectWithScmActionsAndNulls],
+        });
+
+        const result = await jenkinsApi.getProjects(jenkinsInfo);
+
         expect(result).toHaveLength(1);
         expect(result[0].lastBuild!.tests).toEqual({
           total: 635,
diff --git a/plugins/jenkins-backend/src/service/jenkinsApi.ts b/plugins/jenkins-backend/src/service/jenkinsApi.ts
index ddc2bb0ea3..38ab20b17b 100644
--- a/plugins/jenkins-backend/src/service/jenkinsApi.ts
+++ b/plugins/jenkins-backend/src/service/jenkinsApi.ts
@@ -211,7 +211,7 @@ export class JenkinsApiImpl {
       build.actions
         .filter(
           (action: any) =>
-            action._class === 'hudson.plugins.git.util.BuildData',
+            action?._class === 'hudson.plugins.git.util.BuildData',
         )
         .map((action: any) => {
           const [first]: any = Object.values(action.buildsByBranchName);
@@ -253,7 +253,7 @@ export class JenkinsApiImpl {
     const scmInfo: ScmDetails | undefined = project.actions
       .filter(
         (action: any) =>
-          action._class === 'jenkins.scm.api.metadata.ObjectMetadataAction',
+          action?._class === 'jenkins.scm.api.metadata.ObjectMetadataAction',
       )
       .map((action: any) => {
         return {
@@ -272,7 +272,7 @@ export class JenkinsApiImpl {
     const author = project.actions
       .filter(
         (action: any) =>
-          action._class ===
+          action?._class ===
           'jenkins.scm.api.metadata.ContributorMetadataAction',
       )
       .map((action: any) => {
@@ -297,7 +297,7 @@ export class JenkinsApiImpl {
     return build.actions
       .filter(
         (action: any) =>
-          action._class === 'hudson.tasks.junit.TestResultAction',
+          action?._class === 'hudson.tasks.junit.TestResultAction',
       )
       .map((action: any) => {
         return {