diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/PDOM.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/PDOM.java
index 1f02d646a29..3d9680f6d68 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/PDOM.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/PDOM.java
@@ -425,10 +425,13 @@ public class PDOM extends PlatformObject implements IPDOM {
 		db = new Database(fPath, cache, getDefaultVersion(), isPermanentlyReadOnly());
 
 		db.setLocked(lockDB);
-		if (isSupportedVersion()) {
-			readLinkages();
+		try {
+			if (isSupportedVersion()) {
+				readLinkages();
+			}
+		} finally {
+			db.setLocked(lockCount != 0);
 		}
-		db.setLocked(lockCount != 0);
 	}
 
 	public IIndexLocationConverter getLocationConverter() {
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/PDOMManager.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/PDOMManager.java
index 01defac2337..02ac75d1194 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/PDOMManager.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/PDOMManager.java
@@ -384,8 +384,10 @@ public class PDOMManager implements IWritableIndexManager, IListener {
 			WritablePDOM pdom;
 			try {
 				pdom= new WritablePDOM(dbFile, new PDOMProjectIndexLocationConverter(project), getLinkageFactories());
-			} catch (CoreException e) {
-				CCorePlugin.log("Failed to open C/C++ index " + dbFile.getAbsolutePath() //$NON-NLS-1$
+			} catch (CoreException | RuntimeException e) {
+				// Index file is likely corrupted. Recover by rebuilding the index.
+				// See http://bugs.eclipse.org/510054
+				CCorePlugin.log("Failed to open C/C++ index file " + dbFile.getAbsolutePath() //$NON-NLS-1$
 						+ " - rebuilding the index", e); //$NON-NLS-1$
 				dbFile.delete();
 				fromScratch= true;