diff --git a/services/git-bridge/src/main/java/uk/ac/ic/wlgitbridge/bridge/Bridge.java b/services/git-bridge/src/main/java/uk/ac/ic/wlgitbridge/bridge/Bridge.java
index 15752d850b..4faa53ebae 100644
--- a/services/git-bridge/src/main/java/uk/ac/ic/wlgitbridge/bridge/Bridge.java
+++ b/services/git-bridge/src/main/java/uk/ac/ic/wlgitbridge/bridge/Bridge.java
@@ -21,6 +21,7 @@ import uk.ac.ic.wlgitbridge.bridge.swap.job.SwapJobImpl;
 import uk.ac.ic.wlgitbridge.bridge.swap.store.S3SwapStore;
 import uk.ac.ic.wlgitbridge.bridge.swap.store.SwapStore;
 import uk.ac.ic.wlgitbridge.data.CandidateSnapshot;
+import uk.ac.ic.wlgitbridge.data.CannotAcquireLockException;
 import uk.ac.ic.wlgitbridge.data.ProjectLockImpl;
 import uk.ac.ic.wlgitbridge.data.filestore.GitDirectoryContents;
 import uk.ac.ic.wlgitbridge.data.filestore.RawDirectory;
@@ -308,6 +309,8 @@ public class Bridge {
                         projName,
                         new Timestamp(dotGit.lastModified())
                 );
+            } catch (CannotAcquireLockException e) {
+              throw new RuntimeException(e);
             }
         }
     }
@@ -325,7 +328,7 @@ public class Bridge {
     public ProjectRepo getUpdatedRepo(
             Optional<Credential> oauth2,
             String projectName
-    ) throws IOException, GitUserException {
+    ) throws IOException, GitUserException, CannotAcquireLockException {
         try (LockGuard __ = lock.lockGuard(projectName)) {
             Optional<GetDocResult> maybeDoc = snapshotAPI.getDoc(oauth2, projectName);
             if (!maybeDoc.isPresent()) {
@@ -367,7 +370,7 @@ public class Bridge {
             Optional<Credential> oauth2,
             String projectName,
             GetDocResult doc
-    ) throws IOException, GitUserException {
+    ) throws IOException, GitUserException, CannotAcquireLockException {
         ProjectRepo repo;
         ProjectState state = dbStore.getProjectState(projectName);
         switch (state) {
@@ -450,9 +453,10 @@ public class Bridge {
             RawDirectory directoryContents,
             RawDirectory oldDirectoryContents,
             String hostname
-    ) throws SnapshotPostException, IOException, MissingRepositoryException, ForbiddenException, GitUserException {
+    ) throws SnapshotPostException, IOException, MissingRepositoryException, ForbiddenException, GitUserException, CannotAcquireLockException {
         Log.debug("[{}] pushing to Overleaf", projectName);
         try (LockGuard __ = lock.lockGuard(projectName)) {
+            Log.info("[{}] got project lock", projectName);
             pushCritical(
                     oauth2,
                     projectName,
diff --git a/services/git-bridge/src/main/java/uk/ac/ic/wlgitbridge/bridge/gc/GcJobImpl.java b/services/git-bridge/src/main/java/uk/ac/ic/wlgitbridge/bridge/gc/GcJobImpl.java
index 4d72d61e73..37b49432c1 100644
--- a/services/git-bridge/src/main/java/uk/ac/ic/wlgitbridge/bridge/gc/GcJobImpl.java
+++ b/services/git-bridge/src/main/java/uk/ac/ic/wlgitbridge/bridge/gc/GcJobImpl.java
@@ -4,6 +4,7 @@ import uk.ac.ic.wlgitbridge.bridge.lock.LockGuard;
 import uk.ac.ic.wlgitbridge.bridge.lock.ProjectLock;
 import uk.ac.ic.wlgitbridge.bridge.repo.ProjectRepo;
 import uk.ac.ic.wlgitbridge.bridge.repo.RepoStore;
+import uk.ac.ic.wlgitbridge.data.CannotAcquireLockException;
 import uk.ac.ic.wlgitbridge.util.Log;
 import uk.ac.ic.wlgitbridge.util.TimerUtils;
 
@@ -126,6 +127,8 @@ public class GcJobImpl implements GcJob {
                 } catch (IOException e) {
                     Log.warn("[{}] Failed to GC project", proj);
                 }
+            } catch (CannotAcquireLockException e) {
+                Log.warn("[{}] Cannot acquire project lock, skipping GC", proj);
             }
         }
         Log.info("GC job finished, num gcs: {}", numGcs);
diff --git a/services/git-bridge/src/main/java/uk/ac/ic/wlgitbridge/bridge/lock/ProjectLock.java b/services/git-bridge/src/main/java/uk/ac/ic/wlgitbridge/bridge/lock/ProjectLock.java
index 98f6ae96c2..f4617d258c 100644
--- a/services/git-bridge/src/main/java/uk/ac/ic/wlgitbridge/bridge/lock/ProjectLock.java
+++ b/services/git-bridge/src/main/java/uk/ac/ic/wlgitbridge/bridge/lock/ProjectLock.java
@@ -1,5 +1,7 @@
 package uk.ac.ic.wlgitbridge.bridge.lock;
 
+import uk.ac.ic.wlgitbridge.data.CannotAcquireLockException;
+
 /**
  * Project Lock class.
  *
@@ -10,12 +12,12 @@ public interface ProjectLock {
 
     void lockAll();
 
-    void lockForProject(String projectName);
+    void lockForProject(String projectName) throws CannotAcquireLockException;
 
     void unlockForProject(String projectName);
 
     /* RAII hahaha */
-    default LockGuard lockGuard(String projectName) {
+    default LockGuard lockGuard(String projectName) throws CannotAcquireLockException {
         lockForProject(projectName);
         return () -> unlockForProject(projectName);
     }
diff --git a/services/git-bridge/src/main/java/uk/ac/ic/wlgitbridge/bridge/swap/job/SwapJobImpl.java b/services/git-bridge/src/main/java/uk/ac/ic/wlgitbridge/bridge/swap/job/SwapJobImpl.java
index 42585a66c6..6b42cac521 100644
--- a/services/git-bridge/src/main/java/uk/ac/ic/wlgitbridge/bridge/swap/job/SwapJobImpl.java
+++ b/services/git-bridge/src/main/java/uk/ac/ic/wlgitbridge/bridge/swap/job/SwapJobImpl.java
@@ -6,6 +6,7 @@ import uk.ac.ic.wlgitbridge.bridge.lock.LockGuard;
 import uk.ac.ic.wlgitbridge.bridge.lock.ProjectLock;
 import uk.ac.ic.wlgitbridge.bridge.repo.RepoStore;
 import uk.ac.ic.wlgitbridge.bridge.swap.store.SwapStore;
+import uk.ac.ic.wlgitbridge.data.CannotAcquireLockException;
 import uk.ac.ic.wlgitbridge.util.Log;
 import uk.ac.ic.wlgitbridge.util.TimerUtils;
 
@@ -209,6 +210,9 @@ public class SwapJobImpl implements SwapJob {
                 dbStore.swap(projName, compression);
                 repoStore.remove(projName);
             }
+        } catch (CannotAcquireLockException e) {
+            Log.warn("[{}] Cannot acquire project lock, skipping swap", projName);
+            return;
         }
         Log.info("Evicted project: {}", projName);
     }
@@ -256,6 +260,8 @@ public class SwapJobImpl implements SwapJob {
                 swapStore.remove(projName);
                 dbStore.restore(projName);
             }
+        } catch (CannotAcquireLockException e) {
+            throw new RuntimeException(e);
         }
     }
 
diff --git a/services/git-bridge/src/main/java/uk/ac/ic/wlgitbridge/data/CannotAcquireLockException.java b/services/git-bridge/src/main/java/uk/ac/ic/wlgitbridge/data/CannotAcquireLockException.java
new file mode 100644
index 0000000000..79206dd639
--- /dev/null
+++ b/services/git-bridge/src/main/java/uk/ac/ic/wlgitbridge/data/CannotAcquireLockException.java
@@ -0,0 +1,9 @@
+package uk.ac.ic.wlgitbridge.data;
+
+public class CannotAcquireLockException extends Exception {
+    String projectName;
+
+    public CannotAcquireLockException() {
+      super("Another operation is in progress. Please try again later.");
+    }
+}
diff --git a/services/git-bridge/src/main/java/uk/ac/ic/wlgitbridge/data/ProjectLockImpl.java b/services/git-bridge/src/main/java/uk/ac/ic/wlgitbridge/data/ProjectLockImpl.java
index ee6729e916..d9fa8018ca 100644
--- a/services/git-bridge/src/main/java/uk/ac/ic/wlgitbridge/data/ProjectLockImpl.java
+++ b/services/git-bridge/src/main/java/uk/ac/ic/wlgitbridge/data/ProjectLockImpl.java
@@ -4,6 +4,7 @@ import uk.ac.ic.wlgitbridge.bridge.lock.ProjectLock;
 
 import java.util.HashMap;
 import java.util.Map;
+import java.util.concurrent.TimeUnit;
 import java.util.concurrent.locks.Lock;
 import java.util.concurrent.locks.ReentrantLock;
 import java.util.concurrent.locks.ReentrantReadWriteLock;
@@ -35,9 +36,17 @@ public class ProjectLockImpl implements ProjectLock {
     }
 
     @Override
-    public void lockForProject(String projectName) {
+    public void lockForProject(String projectName) throws CannotAcquireLockException {
         Log.debug("[{}] taking project lock", projectName);
-        getLockForProjectName(projectName).lock();
+        Lock projectLock = getLockForProjectName(projectName);
+        try {
+            if (!projectLock.tryLock(5, TimeUnit.SECONDS)) {
+                Log.debug("[{}] failed to acquire project lock", projectName);
+                throw new CannotAcquireLockException();
+            }
+        } catch (InterruptedException e) {
+            throw new RuntimeException(e);
+        }
         Log.debug("[{}] taking reentrant lock", projectName);
         rlock.lock();
         Log.debug("[{}] taken locks", projectName);
diff --git a/services/git-bridge/src/main/java/uk/ac/ic/wlgitbridge/git/handler/WLRepositoryResolver.java b/services/git-bridge/src/main/java/uk/ac/ic/wlgitbridge/git/handler/WLRepositoryResolver.java
index 8057445f90..fdf80806a4 100644
--- a/services/git-bridge/src/main/java/uk/ac/ic/wlgitbridge/git/handler/WLRepositoryResolver.java
+++ b/services/git-bridge/src/main/java/uk/ac/ic/wlgitbridge/git/handler/WLRepositoryResolver.java
@@ -7,6 +7,7 @@ import org.eclipse.jgit.transport.ServiceMayNotContinueException;
 import org.eclipse.jgit.transport.resolver.RepositoryResolver;
 import org.eclipse.jgit.transport.resolver.ServiceNotAuthorizedException;
 import uk.ac.ic.wlgitbridge.bridge.Bridge;
+import uk.ac.ic.wlgitbridge.data.CannotAcquireLockException;
 import uk.ac.ic.wlgitbridge.git.exception.GitUserException;
 import uk.ac.ic.wlgitbridge.git.handler.hook.WriteLatexPutHook;
 import uk.ac.ic.wlgitbridge.git.servlet.WLGitServlet;
@@ -101,6 +102,8 @@ public class WLRepositoryResolver
         } catch (ServiceMayNotContinueException e) {
             /* Such as FailedConnectionException */
             throw e;
+        } catch (CannotAcquireLockException e) {
+            throw new ServiceMayNotContinueException(e.getMessage());
         } catch (RuntimeException e) {
             Log.warn(
                     "Runtime exception when trying to open repo: " + projName,
diff --git a/services/git-bridge/src/main/java/uk/ac/ic/wlgitbridge/git/handler/hook/WriteLatexPutHook.java b/services/git-bridge/src/main/java/uk/ac/ic/wlgitbridge/git/handler/hook/WriteLatexPutHook.java
index 1d0562d17c..9d2a783fc5 100644
--- a/services/git-bridge/src/main/java/uk/ac/ic/wlgitbridge/git/handler/hook/WriteLatexPutHook.java
+++ b/services/git-bridge/src/main/java/uk/ac/ic/wlgitbridge/git/handler/hook/WriteLatexPutHook.java
@@ -8,6 +8,7 @@ import org.eclipse.jgit.transport.ReceiveCommand.Result;
 import org.eclipse.jgit.transport.ReceivePack;
 import uk.ac.ic.wlgitbridge.bridge.Bridge;
 import uk.ac.ic.wlgitbridge.bridge.repo.RepoStore;
+import uk.ac.ic.wlgitbridge.data.CannotAcquireLockException;
 import uk.ac.ic.wlgitbridge.data.filestore.RawDirectory;
 import uk.ac.ic.wlgitbridge.git.exception.GitUserException;
 import uk.ac.ic.wlgitbridge.git.handler.WLReceivePackFactory;
@@ -86,6 +87,13 @@ public class WriteLatexPutHook implements PreReceiveHook {
             } catch (GitUserException e) {
                 Log.error("GitUserException on pre receive", e);
                 handleSnapshotPostException(receivePack, receiveCommand, e);
+            } catch (CannotAcquireLockException e) {
+                Log.info("CannotAcquireLockException on pre receive");
+                receivePack.sendError(e.getMessage());
+                receiveCommand.setResult(
+                  Result.REJECTED_OTHER_REASON,
+                  e.getMessage()
+                );
             } catch (Throwable t) {
                 Log.error("Throwable on pre receive", t);
                 handleSnapshotPostException(
@@ -126,7 +134,7 @@ public class WriteLatexPutHook implements PreReceiveHook {
             Optional<Credential> oauth2,
             Repository repository,
             ReceiveCommand receiveCommand
-    ) throws IOException, GitUserException {
+    ) throws IOException, GitUserException, CannotAcquireLockException {
         checkBranch(receiveCommand);
         checkForcedPush(receiveCommand);
         bridge.push(
diff --git a/services/git-bridge/src/test/java/uk/ac/ic/wlgitbridge/bridge/BridgeTest.java b/services/git-bridge/src/test/java/uk/ac/ic/wlgitbridge/bridge/BridgeTest.java
index 9026973d49..cb94bdf2fb 100644
--- a/services/git-bridge/src/test/java/uk/ac/ic/wlgitbridge/bridge/BridgeTest.java
+++ b/services/git-bridge/src/test/java/uk/ac/ic/wlgitbridge/bridge/BridgeTest.java
@@ -13,6 +13,7 @@ import uk.ac.ic.wlgitbridge.bridge.resource.ResourceCache;
 import uk.ac.ic.wlgitbridge.bridge.snapshot.SnapshotApiFacade;
 import uk.ac.ic.wlgitbridge.bridge.swap.job.SwapJob;
 import uk.ac.ic.wlgitbridge.bridge.swap.store.SwapStore;
+import uk.ac.ic.wlgitbridge.data.CannotAcquireLockException;
 import uk.ac.ic.wlgitbridge.git.exception.GitUserException;
 import uk.ac.ic.wlgitbridge.snapshot.getdoc.GetDocResult;
 
@@ -88,7 +89,7 @@ public class BridgeTest {
 
     @Test
     public void updatingRepositorySetsLastAccessedTime(
-    ) throws IOException, GitUserException {
+    ) throws IOException, GitUserException, CannotAcquireLockException {
         ProjectRepo repo = mock(ProjectRepo.class);
         when(repoStore.getExistingRepo("asdf")).thenReturn(repo);
         when(dbStore.getProjectState("asdf")).thenReturn(ProjectState.PRESENT);
diff --git a/services/git-bridge/src/test/java/uk/ac/ic/wlgitbridge/bridge/gc/GcJobImplTest.java b/services/git-bridge/src/test/java/uk/ac/ic/wlgitbridge/bridge/gc/GcJobImplTest.java
index 091e6b5692..4db48f91d0 100644
--- a/services/git-bridge/src/test/java/uk/ac/ic/wlgitbridge/bridge/gc/GcJobImplTest.java
+++ b/services/git-bridge/src/test/java/uk/ac/ic/wlgitbridge/bridge/gc/GcJobImplTest.java
@@ -8,6 +8,7 @@ import uk.ac.ic.wlgitbridge.bridge.lock.LockGuard;
 import uk.ac.ic.wlgitbridge.bridge.lock.ProjectLock;
 import uk.ac.ic.wlgitbridge.bridge.repo.ProjectRepo;
 import uk.ac.ic.wlgitbridge.bridge.repo.RepoStore;
+import uk.ac.ic.wlgitbridge.data.CannotAcquireLockException;
 import uk.ac.ic.wlgitbridge.data.ProjectLockImpl;
 
 import java.io.IOException;
@@ -112,6 +113,8 @@ public class GcJobImplTest {
                 assertFalse(fut.isDone());
                 Thread.sleep(1);
             }
+        } catch (CannotAcquireLockException e) {
+            throw new RuntimeException(e);
         }
         /* Now that we've released the lock, fut should complete */
         fut.join();