diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/FailedToReAcquireLockException.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/FailedToReAcquireLockException.java
index 4ffc1ccdeb8..978bb845e02 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/FailedToReAcquireLockException.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/FailedToReAcquireLockException.java
@@ -16,27 +16,26 @@
 /**
  * This exception is raised when {@link YieldableIndexLock#yield()} fails to
  * reacquire the lock after yielding, this may be due to an {@link InterruptedException}
- * or an {@link OperationCanceledException} which will be the nested exception.
+ * or an {@link OperationCanceledException} or some other type of runtime exception or
+ * error (especially assertion errors) which will be the nested exception.
  */
 public class FailedToReAcquireLockException extends Exception {
 
-	public FailedToReAcquireLockException(InterruptedException e) {
-		super(e);
-		Assert.isNotNull(e);
+	public FailedToReAcquireLockException(Throwable t) {
+		super(t);
+		Assert.isNotNull(t);
 	}
 
-	public FailedToReAcquireLockException(OperationCanceledException e) {
-		super(e);
-		Assert.isNotNull(e);
-	}
-
-	public void reThrow() throws InterruptedException, OperationCanceledException {
+	public void reThrow() throws InterruptedException {
 		if (getCause() instanceof InterruptedException ie) {
 			throw ie;
 		}
-		if (getCause() instanceof OperationCanceledException oce) {
-			throw oce;
+		if (getCause() instanceof RuntimeException re) {
+			throw re;
+		}
+		if (getCause() instanceof Error er) {
+			throw er;
 		}
-		throw new RuntimeException("Unexpectedly the exception cause was none of the allowed types", this); //$NON-NLS-1$
+		throw new RuntimeException("Checked exception changed wrapped in runtime exception", getCause()); //$NON-NLS-1$
 	}
 }
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/PDOMWriter.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/PDOMWriter.java
index 6f26581a1cd..aeacf59a44a 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/PDOMWriter.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/PDOMWriter.java
@@ -645,6 +645,7 @@ private IIndexFragmentFile storeFileInIndex(Data data, FileInAST astFile, int st
 		ISignificantMacros significantMacros = fileKey.getSignificantMacros();
 		IIndexFragmentFile oldFile = index.getWritableFile(storageLinkageID, location, significantMacros);
 		file = index.addUncommittedFile(storageLinkageID, location, significantMacros);
+		boolean hasLock = true;
 		try {
 			boolean pragmaOnce = owner != null ? owner.hasPragmaOnceSemantics() : data.fAST.hasPragmaOnceSemantics();
 			file.setPragmaOnceSemantics(pragmaOnce);
@@ -695,8 +696,25 @@ private IIndexFragmentFile storeFileInIndex(Data data, FileInAST astFile, int st
 			file.setSizeAndEncodingHashcode(computeFileSizeAndEncodingHashcode(astFile.fileSize, location));
 			file.setContentsHash(astFile.contentsHash);
 			file = index.commitUncommittedFile();
+		} catch (FailedToReAcquireLockException e) {
+			hasLock = false;
+			throw e;
 		} finally {
-			index.clearUncommittedFile();
+			try {
+				// Without the lock we need to still do some cleanup, but some
+				// of it will fail with an assertion error when running unit tests
+				// so to not lose the original exception, we suppress it if
+				// we don't have the lock.
+				index.clearUncommittedFile();
+			} catch (Throwable e) {
+				if (hasLock) {
+					throw e;
+				} else {
+					CCorePlugin.log(
+							"Exception hit in finally block while dealing with active FailedToReAcquireLockException", //$NON-NLS-1$
+							e);
+				}
+			}
 		}
 		return file;
 	}
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/YieldableIndexLock.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/YieldableIndexLock.java
index 618ffd175c2..cbafbcb494a 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/YieldableIndexLock.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/YieldableIndexLock.java
@@ -15,7 +15,6 @@
 
 import org.eclipse.cdt.internal.core.index.IWritableIndex;
 import org.eclipse.core.runtime.IProgressMonitor;
-import org.eclipse.core.runtime.OperationCanceledException;
 
 /**
  * Write lock on the index that can be yielded temporarily to unblock threads that need
@@ -67,10 +66,8 @@ public void yield() throws FailedToReAcquireLockException {
 			lastLockTime = 0;
 			try {
 				acquire();
-			} catch (OperationCanceledException e) {
-				throw new FailedToReAcquireLockException(e);
-			} catch (InterruptedException e) {
-				throw new FailedToReAcquireLockException(e);
+			} catch (Throwable t) {
+				throw new FailedToReAcquireLockException(t);
 			}
 		}
 	}