diff --git a/lib/workers/repository/cache.ts b/lib/workers/repository/cache.ts
index 6ba4ef089a314052d95237a9a08a93db6b5e2856..a539dc8727ab27c04bc5e5332b58906623468fd1 100644
--- a/lib/workers/repository/cache.ts
+++ b/lib/workers/repository/cache.ts
@@ -53,7 +53,14 @@ async function generateBranchCache(branch: BranchConfig): Promise<BranchCache> {
       }
     }
     const automerge = !!branch.automerge;
-    const isModified = sha ? await isBranchModified(branchName) : false;
+    let isModified = false;
+    if (sha) {
+      try {
+        isModified = await isBranchModified(branchName);
+      } catch (err) /* istanbul ignore next */ {
+        // Do nothing
+      }
+    }
     const upgrades: BranchUpgradeCache[] = branch.upgrades
       ? branch.upgrades.map(generateBranchUpgradeCache)
       : [];