diff --git a/lib/platform/gitlab/index.js b/lib/platform/gitlab/index.js
index a5e9805b26525edb8905223d26e9fb77d0af27b0..939579d02206b7d8e986486ce048cba1de4cbf0e 100644
--- a/lib/platform/gitlab/index.js
+++ b/lib/platform/gitlab/index.js
@@ -190,6 +190,9 @@ function isBranchStale() {
 // Returns the Pull Request for a branch. Null if not exists.
 async function getBranchPr(branchName) {
   logger.debug(`getBranchPr(${branchName})`);
+  if (!await branchExists(branchName)) {
+    return null;
+  }
   const urlString = `projects/${
     config.repository
   }/merge_requests?state=opened&per_page=100`;
@@ -463,9 +466,18 @@ async function getPr(iid) {
   const branchUrl = `projects/${
     config.repository
   }/repository/branches/${urlEscape(pr.source_branch)}`;
-  const branch = (await get(branchUrl)).body;
-  if (branch && branch.commit && branch.commit.author_email === config.email) {
-    pr.canRebase = true;
+  try {
+    const branch = (await get(branchUrl)).body;
+    if (
+      branch &&
+      branch.commit &&
+      branch.commit.author_email === config.email
+    ) {
+      pr.canRebase = true;
+    }
+  } catch (err) {
+    logger.warn({ err }, 'Error getting PR branch');
+    pr.isUnmergeable = true;
   }
   return pr;
 }
diff --git a/lib/workers/branch/index.js b/lib/workers/branch/index.js
index f32a4a597a9b8cabbce383b0a516bdbb633fd5da..16ff277b07f3efd4560cb5e21933bec8b0dc5485 100644
--- a/lib/workers/branch/index.js
+++ b/lib/workers/branch/index.js
@@ -77,8 +77,10 @@ async function processBranch(branchConfig) {
       }
       return 'already-existed';
     }
-    logger.debug('Checking if PR has been edited');
-    pr = await platform.findPr(config.branchName, config.prTitle, 'open');
+    if (branchExists) {
+      logger.debug('Checking if PR has been edited');
+      pr = await platform.findPr(config.branchName, config.prTitle, 'open');
+    }
     if (pr) {
       logger.debug({ pr }, 'Found existing PR');
       pr = await platform.getPr(pr.number);
diff --git a/test/platform/gitlab/__snapshots__/index.spec.js.snap b/test/platform/gitlab/__snapshots__/index.spec.js.snap
index f9bdbd1b57770b0a82c29c564d92a341100a64fd..e19ed8345f1bef098ebc0f422b9f357a25638005 100644
--- a/test/platform/gitlab/__snapshots__/index.spec.js.snap
+++ b/test/platform/gitlab/__snapshots__/index.spec.js.snap
@@ -133,35 +133,7 @@ Array [
 
 exports[`platform/gitlab getBranchLastCommitTime should return a Date 1`] = `2012-09-20T08:50:22.000Z`;
 
-exports[`platform/gitlab getBranchPr(branchName) should return null if no PR exists 1`] = `
-Array [
-  Array [
-    "projects/undefined/merge_requests?state=opened&per_page=100",
-    Object {
-      "paginate": true,
-    },
-  ],
-]
-`;
-
 exports[`platform/gitlab getBranchPr(branchName) should return the PR object 1`] = `
-Array [
-  Array [
-    "projects/undefined/merge_requests?state=opened&per_page=100",
-    Object {
-      "paginate": true,
-    },
-  ],
-  Array [
-    "projects/undefined/merge_requests/undefined",
-  ],
-  Array [
-    "projects/undefined/repository/branches/some-branch",
-  ],
-]
-`;
-
-exports[`platform/gitlab getBranchPr(branchName) should return the PR object 2`] = `
 Object {
   "additions": 1,
   "base": Object {
@@ -221,6 +193,23 @@ Object {
 }
 `;
 
+exports[`platform/gitlab getPr(prNo) returns the PR with nonexisting branch 1`] = `
+Object {
+  "body": "a merge request",
+  "branchName": "some-branch",
+  "canMerge": false,
+  "description": "a merge request",
+  "displayNumber": "Merge Request #12345",
+  "id": 1,
+  "iid": 12345,
+  "isUnmergeable": true,
+  "merge_status": "cannot_be_merged",
+  "number": 12345,
+  "source_branch": "some-branch",
+  "state": "open",
+}
+`;
+
 exports[`platform/gitlab getRepos should return an array of repos 1`] = `
 Array [
   Array [
diff --git a/test/platform/gitlab/index.spec.js b/test/platform/gitlab/index.spec.js
index 5b904396aa9cde2c4b313cf07c9a6fd62207e7dc..94bca4325e71073dbe01e1b5c2b297a15ff3eb26 100644
--- a/test/platform/gitlab/index.spec.js
+++ b/test/platform/gitlab/index.spec.js
@@ -240,15 +240,22 @@ describe('platform/gitlab', () => {
     });
   });
   describe('getBranchPr(branchName)', () => {
+    it('should return null if branch does not exist', async () => {
+      get.mockReturnValueOnce({ statusCode: 500 }); // branchExists
+      const pr = await gitlab.getBranchPr('somebranch');
+      expect(pr).toBe(null);
+    });
     it('should return null if no PR exists', async () => {
-      get.mockImplementationOnce(() => ({
+      get.mockReturnValueOnce({ statusCode: 200 }); // branchExists
+      get.mockReturnValueOnce({
+        // branchExists
         body: [],
-      }));
+      });
       const pr = await gitlab.getBranchPr('somebranch');
-      expect(get.mock.calls).toMatchSnapshot();
       expect(pr).toBe(null);
     });
     it('should return the PR object', async () => {
+      get.mockReturnValueOnce({ statusCode: 200 }); // branchExists
       get.mockReturnValueOnce({
         body: [{ number: 91, source_branch: 'somebranch' }],
       });
@@ -266,7 +273,6 @@ describe('platform/gitlab', () => {
       });
       get.mockReturnValueOnce({ body: 'foo' });
       const pr = await gitlab.getBranchPr('somebranch');
-      expect(get.mock.calls).toMatchSnapshot();
       expect(pr).toMatchSnapshot();
     });
   });
@@ -584,6 +590,25 @@ describe('platform/gitlab', () => {
       const pr = await gitlab.getPr(12345);
       expect(pr).toMatchSnapshot();
     });
+    it('returns the PR with nonexisting branch', async () => {
+      get.mockImplementationOnce(() => ({
+        body: {
+          id: 1,
+          iid: 12345,
+          description: 'a merge request',
+          state: 'open',
+          merge_status: 'cannot_be_merged',
+          source_branch: 'some-branch',
+        },
+      }));
+      get.mockImplementationOnce(() =>
+        Promise.reject({
+          statusCode: 404,
+        })
+      );
+      const pr = await gitlab.getPr(12345);
+      expect(pr).toMatchSnapshot();
+    });
   });
   describe('getPrFiles()', () => {
     it('should return empty', async () => {