diff --git a/src/plugins/debugger/cdb/cdbdebugengine.cpp b/src/plugins/debugger/cdb/cdbdebugengine.cpp
index 6559c964d04..babce3a0f09 100644
--- a/src/plugins/debugger/cdb/cdbdebugengine.cpp
+++ b/src/plugins/debugger/cdb/cdbdebugengine.cpp
@@ -886,7 +886,8 @@ void CdbDebugEngine::stepExec()
 
     m_d->clearForRun();
     const HRESULT hr = m_d->m_cif.debugControl->SetExecutionStatus(DEBUG_STATUS_STEP_INTO);
-    Q_UNUSED(hr)
+    if (FAILED(hr))
+        qWarning("%s : %s", Q_FUNC_INFO, qPrintable(msgComFailed("SetExecutionStatus", hr)));
 
     m_d->m_breakEventMode = CdbDebugEnginePrivate::BreakEventIgnoreOnce;
     startWatchTimer();
diff --git a/src/plugins/debugger/cdb/cdbdebugeventcallback.cpp b/src/plugins/debugger/cdb/cdbdebugeventcallback.cpp
index eefb0bd06c9..0d621969dfd 100644
--- a/src/plugins/debugger/cdb/cdbdebugeventcallback.cpp
+++ b/src/plugins/debugger/cdb/cdbdebugeventcallback.cpp
@@ -34,7 +34,8 @@
 #include "breakhandler.h"
 #include "cdbstacktracecontext.h"
 
-enum { cppExceptionCode = 0xe06d7363, startupCompleteTrap = 0x406d1388 };
+enum { cppExceptionCode = 0xe06d7363, startupCompleteTrap = 0x406d1388,
+       rpcServerUnavailableExceptionCode = 0x6ba };
 
 #include <QtCore/QDebug>
 #include <QtCore/QTextStream>
@@ -345,6 +346,7 @@ static bool isFatalException(LONG code)
     case EXCEPTION_BREAKPOINT:
     case EXCEPTION_SINGLE_STEP:
     case startupCompleteTrap: // Mysterious exception at start of application
+    case rpcServerUnavailableExceptionCode:
         return false;
     default:
         break;
diff --git a/src/plugins/debugger/cdb/cdbstacktracecontext.cpp b/src/plugins/debugger/cdb/cdbstacktracecontext.cpp
index 3f72f268f86..8b842639346 100644
--- a/src/plugins/debugger/cdb/cdbstacktracecontext.cpp
+++ b/src/plugins/debugger/cdb/cdbstacktracecontext.cpp
@@ -139,6 +139,12 @@ int CdbStackTraceContext::indexOf(const QString &function) const
     return -1;
 }
 
+static inline QString msgFrameContextFailed(int index, const StackFrame &f, const QString &why)
+{
+    return QString::fromLatin1("Unable to create stack frame context #%1, %2:%3 (%4): %5").
+            arg(index).arg(f.function).arg(f.line).arg(f.file, why);
+}
+
 CdbStackFrameContext *CdbStackTraceContext::frameContextAt(int index, QString *errorMessage)
 {
     // Create a frame on demand
@@ -153,11 +159,15 @@ CdbStackFrameContext *CdbStackTraceContext::frameContextAt(int index, QString *e
     if (m_frameContexts.at(index))
         return m_frameContexts.at(index);
     CIDebugSymbolGroup *sg  = createSymbolGroup(index, errorMessage);
-    if (!sg)
+    if (!sg) {
+        *errorMessage = msgFrameContextFailed(index, m_frames.at(index), *errorMessage);
         return 0;
+    }
     CdbSymbolGroupContext *sc = CdbSymbolGroupContext::create(QLatin1String("local"), sg, errorMessage);
-    if (!sc)
+    if (!sc) {
+        *errorMessage = msgFrameContextFailed(index, m_frames.at(index), *errorMessage);
         return 0;
+    }
     CdbStackFrameContext *fr = new CdbStackFrameContext(m_dumper, sc);
     m_frameContexts[index] = fr;
     return fr;
diff --git a/src/plugins/debugger/cdb/cdbsymbolgroupcontext.cpp b/src/plugins/debugger/cdb/cdbsymbolgroupcontext.cpp
index 25931005ddd..2fa25c1c12e 100644
--- a/src/plugins/debugger/cdb/cdbsymbolgroupcontext.cpp
+++ b/src/plugins/debugger/cdb/cdbsymbolgroupcontext.cpp
@@ -112,7 +112,8 @@ CdbSymbolGroupContext::CdbSymbolGroupContext(const QString &prefix,
                                              CIDebugSymbolGroup *symbolGroup) :
     m_prefix(prefix),
     m_nameDelimiter(QLatin1Char('.')),
-    m_symbolGroup(symbolGroup)
+    m_symbolGroup(symbolGroup),
+    m_unnamedSymbolNumber(1)
 {
 }
 
@@ -143,15 +144,17 @@ bool CdbSymbolGroupContext::init(QString *errorMessage)
         return false;
     }
 
-    m_symbolParameters.reserve(3u * count);
-    m_symbolParameters.resize(count);
+    if (count) {
+        m_symbolParameters.reserve(3u * count);
+        m_symbolParameters.resize(count);
 
-    hr = m_symbolGroup->GetSymbolParameters(0, count, symbolParameters());
-    if (FAILED(hr)) {
-        *errorMessage = msgComFailed("GetSymbolParameters", hr);
-        return false;
+        hr = m_symbolGroup->GetSymbolParameters(0, count, symbolParameters());
+        if (FAILED(hr)) {
+            *errorMessage = QString::fromLatin1("In %1: %2 (%3 symbols)").arg(QLatin1String(Q_FUNC_INFO), msgComFailed("GetSymbolParameters", hr)).arg(count);
+            return false;
+        }
+        populateINameIndexMap(m_prefix, DEBUG_ANY_ID, 0, count);
     }
-    populateINameIndexMap(m_prefix, DEBUG_ANY_ID, 0, count);
     if (debug)
         qDebug() << Q_FUNC_INFO << '\n'<< toString();
     return true;
@@ -172,7 +175,15 @@ void CdbSymbolGroupContext::populateINameIndexMap(const QString &prefix, unsigne
         const DEBUG_SYMBOL_PARAMETERS &p = m_symbolParameters.at(i);
         if (parentId == p.ParentSymbol) {
             seenChildren++;
-            const QString name = symbolPrefix + getSymbolString(m_symbolGroup, &IDebugSymbolGroup2::GetSymbolNameWide, i);
+            // "__formal" occurs when someone writes "void foo(int /* x */)..."
+            static const QString unnamedFormalParameter = QLatin1String("__formal");
+            QString symbolName = getSymbolString(m_symbolGroup, &IDebugSymbolGroup2::GetSymbolNameWide, i);
+            if (symbolName == unnamedFormalParameter) {
+                symbolName = QLatin1String("<unnamed");
+                symbolName += QString::number(m_unnamedSymbolNumber++);
+                symbolName += QLatin1Char('>');
+            }
+            const QString name = symbolPrefix + symbolName;
             m_inameIndexMap.insert(name, i);
             if (getSymbolState(p) == ExpandedSymbol)
                 populateINameIndexMap(name, i, i + 1, p.SubElements);
@@ -215,7 +226,7 @@ CdbSymbolGroupContext::SymbolState CdbSymbolGroupContext::symbolState(const QStr
         return ExpandedSymbol;
     unsigned long index;
     if (!lookupPrefix(prefix, &index)) {
-        qWarning("WARNING %s: %s\n", Q_FUNC_INFO, msgSymbolNotFound(prefix));
+        qWarning("WARNING %s: %s\n", Q_FUNC_INFO, qPrintable(msgSymbolNotFound(prefix)));
         return LeafSymbol;
     }
     return symbolState(index);
@@ -265,6 +276,11 @@ bool CdbSymbolGroupContext::getChildSymbolsPosition(const QString &prefix,
     return true;
 }
 
+static inline QString msgExpandFailed(const QString &prefix, unsigned long index, const QString &why)
+{
+    return QString::fromLatin1("Unable to expand '%1' %2: %3").arg(prefix).arg(index).arg(why);
+}
+
 // Expand a symbol using the symbol group interface.
 bool CdbSymbolGroupContext::expandSymbol(const QString &prefix, unsigned long index, QString *errorMessage)
 {
@@ -283,8 +299,7 @@ bool CdbSymbolGroupContext::expandSymbol(const QString &prefix, unsigned long in
 
     HRESULT hr = m_symbolGroup->ExpandSymbol(index, TRUE);
     if (FAILED(hr)) {
-        *errorMessage = QString::fromLatin1("Unable to expand '%1' %2: %3").
-                        arg(prefix).arg(index).arg(msgComFailed("ExpandSymbol", hr));
+        *errorMessage = msgExpandFailed(prefix, index, msgComFailed("ExpandSymbol", hr));
         return false;
     }
     // Hopefully, this will never fail, else data structure will be foobar.
@@ -292,7 +307,7 @@ bool CdbSymbolGroupContext::expandSymbol(const QString &prefix, unsigned long in
     ULONG newSize;
     hr = m_symbolGroup->GetNumberSymbols(&newSize);
     if (FAILED(hr)) {
-        *errorMessage = msgComFailed("GetNumberSymbols", hr);
+        *errorMessage = msgExpandFailed(prefix, index, msgComFailed("GetNumberSymbols", hr));
         return false;
     }
 
@@ -302,7 +317,7 @@ bool CdbSymbolGroupContext::expandSymbol(const QString &prefix, unsigned long in
 
     hr = m_symbolGroup->GetSymbolParameters(0, newSize, symbolParameters());
     if (FAILED(hr)) {
-        *errorMessage = msgComFailed("GetSymbolParameters", hr);
+        *errorMessage = msgExpandFailed(prefix, index, msgComFailed("GetSymbolParameters", hr));
         return false;
     }
     // The new symbols are inserted after the parent symbol.
diff --git a/src/plugins/debugger/cdb/cdbsymbolgroupcontext.h b/src/plugins/debugger/cdb/cdbsymbolgroupcontext.h
index ef8f939c71c..ca9cbadd651 100644
--- a/src/plugins/debugger/cdb/cdbsymbolgroupcontext.h
+++ b/src/plugins/debugger/cdb/cdbsymbolgroupcontext.h
@@ -132,6 +132,7 @@ private:
     CIDebugSymbolGroup *m_symbolGroup;
     NameIndexMap m_inameIndexMap;
     QVector<DEBUG_SYMBOL_PARAMETERS> m_symbolParameters;
+    int m_unnamedSymbolNumber;
 };
 
 // Helper to a sequence of  WatchData into a list.