diff --git a/extern/cloop/src/tests/test1/CalcCppApi.h b/extern/cloop/src/tests/test1/CalcCppApi.h
index bf2d7311e0..3ea664c617 100644
--- a/extern/cloop/src/tests/test1/CalcCppApi.h
+++ b/extern/cloop/src/tests/test1/CalcCppApi.h
@@ -7,6 +7,23 @@
 #define CLOOP_CARG
 #endif
 
+#ifndef CLOOP_NOEXCEPT
+#if __cplusplus >= 201103L
+#define CLOOP_NOEXCEPT noexcept
+#else
+#define CLOOP_NOEXCEPT throw()
+#endif
+#endif
+
+
+#ifndef CLOOP_CONSTEXPR
+#if __cplusplus >= 201103L
+#define CLOOP_CONSTEXPR constexpr
+#else
+#define CLOOP_CONSTEXPR const
+#endif
+#endif
+
 
 namespace calc
 {
@@ -34,6 +51,8 @@ namespace calc
 
 	// Interfaces declarations
 
+#define CALC_IDISPOSABLE_VERSION 1u
+
 	class IDisposable
 	{
 	public:
@@ -41,7 +60,7 @@ namespace calc
 		{
 			void* cloopDummy[1];
 			uintptr_t version;
-			void (CLOOP_CARG *dispose)(IDisposable* self) throw();
+			void (CLOOP_CARG *dispose)(IDisposable* self) CLOOP_NOEXCEPT;
 		};
 
 		void* cloopDummy[1];
@@ -57,7 +76,7 @@ namespace calc
 		}
 
 	public:
-		static const unsigned VERSION = 1;
+		static CLOOP_CONSTEXPR unsigned VERSION = CALC_IDISPOSABLE_VERSION;
 
 		void dispose()
 		{
@@ -65,13 +84,15 @@ namespace calc
 		}
 	};
 
+#define CALC_ISTATUS_VERSION 2u
+
 	class IStatus : public IDisposable
 	{
 	public:
 		struct VTable : public IDisposable::VTable
 		{
-			int (CLOOP_CARG *getCode)(const IStatus* self) throw();
-			void (CLOOP_CARG *setCode)(IStatus* self, int code) throw();
+			int (CLOOP_CARG *getCode)(const IStatus* self) CLOOP_NOEXCEPT;
+			void (CLOOP_CARG *setCode)(IStatus* self, int code) CLOOP_NOEXCEPT;
 		};
 
 	protected:
@@ -85,11 +106,11 @@ namespace calc
 		}
 
 	public:
-		static const unsigned VERSION = 2;
+		static CLOOP_CONSTEXPR unsigned VERSION = CALC_ISTATUS_VERSION;
 
-		static const int ERROR_1 = 1;
-		static const int ERROR_2 = 0x2;
-		static const int ERROR_12 = IStatus::ERROR_1 | IStatus::ERROR_2;
+		static CLOOP_CONSTEXPR int ERROR_1 = 1;
+		static CLOOP_CONSTEXPR int ERROR_2 = 0x2;
+		static CLOOP_CONSTEXPR int ERROR_12 = IStatus::ERROR_1 | IStatus::ERROR_2;
 
 		int getCode() const
 		{
@@ -103,15 +124,17 @@ namespace calc
 		}
 	};
 
+#define CALC_IFACTORY_VERSION 2u
+
 	class IFactory : public IDisposable
 	{
 	public:
 		struct VTable : public IDisposable::VTable
 		{
-			IStatus* (CLOOP_CARG *createStatus)(IFactory* self) throw();
-			ICalculator* (CLOOP_CARG *createCalculator)(IFactory* self, IStatus* status) throw();
-			ICalculator2* (CLOOP_CARG *createCalculator2)(IFactory* self, IStatus* status) throw();
-			ICalculator* (CLOOP_CARG *createBrokenCalculator)(IFactory* self, IStatus* status) throw();
+			IStatus* (CLOOP_CARG *createStatus)(IFactory* self) CLOOP_NOEXCEPT;
+			ICalculator* (CLOOP_CARG *createCalculator)(IFactory* self, IStatus* status) CLOOP_NOEXCEPT;
+			ICalculator2* (CLOOP_CARG *createCalculator2)(IFactory* self, IStatus* status) CLOOP_NOEXCEPT;
+			ICalculator* (CLOOP_CARG *createBrokenCalculator)(IFactory* self, IStatus* status) CLOOP_NOEXCEPT;
 		};
 
 	protected:
@@ -125,7 +148,7 @@ namespace calc
 		}
 
 	public:
-		static const unsigned VERSION = 2;
+		static CLOOP_CONSTEXPR unsigned VERSION = CALC_IFACTORY_VERSION;
 
 		IStatus* createStatus()
 		{
@@ -158,15 +181,17 @@ namespace calc
 		}
 	};
 
+#define CALC_ICALCULATOR_VERSION 4u
+
 	class ICalculator : public IDisposable
 	{
 	public:
 		struct VTable : public IDisposable::VTable
 		{
-			int (CLOOP_CARG *sum)(const ICalculator* self, IStatus* status, int n1, int n2) throw();
-			int (CLOOP_CARG *getMemory)(const ICalculator* self) throw();
-			void (CLOOP_CARG *setMemory)(ICalculator* self, int n) throw();
-			void (CLOOP_CARG *sumAndStore)(ICalculator* self, IStatus* status, int n1, int n2) throw();
+			int (CLOOP_CARG *sum)(const ICalculator* self, IStatus* status, int n1, int n2) CLOOP_NOEXCEPT;
+			int (CLOOP_CARG *getMemory)(const ICalculator* self) CLOOP_NOEXCEPT;
+			void (CLOOP_CARG *setMemory)(ICalculator* self, int n) CLOOP_NOEXCEPT;
+			void (CLOOP_CARG *sumAndStore)(ICalculator* self, IStatus* status, int n1, int n2) CLOOP_NOEXCEPT;
 		};
 
 	protected:
@@ -180,7 +205,7 @@ namespace calc
 		}
 
 	public:
-		static const unsigned VERSION = 4;
+		static CLOOP_CONSTEXPR unsigned VERSION = CALC_ICALCULATOR_VERSION;
 
 		template <typename StatusType> int sum(StatusType* status, int n1, int n2) const
 		{
@@ -223,14 +248,16 @@ namespace calc
 		}
 	};
 
+#define CALC_ICALCULATOR2_VERSION 6u
+
 	class ICalculator2 : public ICalculator
 	{
 	public:
 		struct VTable : public ICalculator::VTable
 		{
-			int (CLOOP_CARG *multiply)(const ICalculator2* self, IStatus* status, int n1, int n2) throw();
-			void (CLOOP_CARG *copyMemory)(ICalculator2* self, const ICalculator* calculator) throw();
-			void (CLOOP_CARG *copyMemory2)(ICalculator2* self, const int* address) throw();
+			int (CLOOP_CARG *multiply)(const ICalculator2* self, IStatus* status, int n1, int n2) CLOOP_NOEXCEPT;
+			void (CLOOP_CARG *copyMemory)(ICalculator2* self, const ICalculator* calculator) CLOOP_NOEXCEPT;
+			void (CLOOP_CARG *copyMemory2)(ICalculator2* self, const int* address) CLOOP_NOEXCEPT;
 		};
 
 	protected:
@@ -244,7 +271,7 @@ namespace calc
 		}
 
 	public:
-		static const unsigned VERSION = 6;
+		static CLOOP_CONSTEXPR unsigned VERSION = CALC_ICALCULATOR2_VERSION;
 
 		template <typename StatusType> int multiply(StatusType* status, int n1, int n2) const
 		{
@@ -291,7 +318,7 @@ namespace calc
 			this->cloopVTable = &vTable;
 		}
 
-		static void CLOOP_CARG cloopdisposeDispatcher(IDisposable* self) throw()
+		static void CLOOP_CARG cloopdisposeDispatcher(IDisposable* self) CLOOP_NOEXCEPT
 		{
 			try
 			{
@@ -342,7 +369,7 @@ namespace calc
 			this->cloopVTable = &vTable;
 		}
 
-		static int CLOOP_CARG cloopgetCodeDispatcher(const IStatus* self) throw()
+		static int CLOOP_CARG cloopgetCodeDispatcher(const IStatus* self) CLOOP_NOEXCEPT
 		{
 			try
 			{
@@ -355,7 +382,7 @@ namespace calc
 			}
 		}
 
-		static void CLOOP_CARG cloopsetCodeDispatcher(IStatus* self, int code) throw()
+		static void CLOOP_CARG cloopsetCodeDispatcher(IStatus* self, int code) CLOOP_NOEXCEPT
 		{
 			try
 			{
@@ -367,7 +394,7 @@ namespace calc
 			}
 		}
 
-		static void CLOOP_CARG cloopdisposeDispatcher(IDisposable* self) throw()
+		static void CLOOP_CARG cloopdisposeDispatcher(IDisposable* self) CLOOP_NOEXCEPT
 		{
 			try
 			{
@@ -421,7 +448,7 @@ namespace calc
 			this->cloopVTable = &vTable;
 		}
 
-		static IStatus* CLOOP_CARG cloopcreateStatusDispatcher(IFactory* self) throw()
+		static IStatus* CLOOP_CARG cloopcreateStatusDispatcher(IFactory* self) CLOOP_NOEXCEPT
 		{
 			try
 			{
@@ -434,7 +461,7 @@ namespace calc
 			}
 		}
 
-		static ICalculator* CLOOP_CARG cloopcreateCalculatorDispatcher(IFactory* self, IStatus* status) throw()
+		static ICalculator* CLOOP_CARG cloopcreateCalculatorDispatcher(IFactory* self, IStatus* status) CLOOP_NOEXCEPT
 		{
 			StatusType status2(status);
 
@@ -449,7 +476,7 @@ namespace calc
 			}
 		}
 
-		static ICalculator2* CLOOP_CARG cloopcreateCalculator2Dispatcher(IFactory* self, IStatus* status) throw()
+		static ICalculator2* CLOOP_CARG cloopcreateCalculator2Dispatcher(IFactory* self, IStatus* status) CLOOP_NOEXCEPT
 		{
 			StatusType status2(status);
 
@@ -464,7 +491,7 @@ namespace calc
 			}
 		}
 
-		static ICalculator* CLOOP_CARG cloopcreateBrokenCalculatorDispatcher(IFactory* self, IStatus* status) throw()
+		static ICalculator* CLOOP_CARG cloopcreateBrokenCalculatorDispatcher(IFactory* self, IStatus* status) CLOOP_NOEXCEPT
 		{
 			StatusType status2(status);
 
@@ -479,7 +506,7 @@ namespace calc
 			}
 		}
 
-		static void CLOOP_CARG cloopdisposeDispatcher(IDisposable* self) throw()
+		static void CLOOP_CARG cloopdisposeDispatcher(IDisposable* self) CLOOP_NOEXCEPT
 		{
 			try
 			{
@@ -535,7 +562,7 @@ namespace calc
 			this->cloopVTable = &vTable;
 		}
 
-		static int CLOOP_CARG cloopsumDispatcher(const ICalculator* self, IStatus* status, int n1, int n2) throw()
+		static int CLOOP_CARG cloopsumDispatcher(const ICalculator* self, IStatus* status, int n1, int n2) CLOOP_NOEXCEPT
 		{
 			StatusType status2(status);
 
@@ -550,7 +577,7 @@ namespace calc
 			}
 		}
 
-		static int CLOOP_CARG cloopgetMemoryDispatcher(const ICalculator* self) throw()
+		static int CLOOP_CARG cloopgetMemoryDispatcher(const ICalculator* self) CLOOP_NOEXCEPT
 		{
 			try
 			{
@@ -563,7 +590,7 @@ namespace calc
 			}
 		}
 
-		static void CLOOP_CARG cloopsetMemoryDispatcher(ICalculator* self, int n) throw()
+		static void CLOOP_CARG cloopsetMemoryDispatcher(ICalculator* self, int n) CLOOP_NOEXCEPT
 		{
 			try
 			{
@@ -575,7 +602,7 @@ namespace calc
 			}
 		}
 
-		static void CLOOP_CARG cloopsumAndStoreDispatcher(ICalculator* self, IStatus* status, int n1, int n2) throw()
+		static void CLOOP_CARG cloopsumAndStoreDispatcher(ICalculator* self, IStatus* status, int n1, int n2) CLOOP_NOEXCEPT
 		{
 			StatusType status2(status);
 
@@ -589,7 +616,7 @@ namespace calc
 			}
 		}
 
-		static void CLOOP_CARG cloopdisposeDispatcher(IDisposable* self) throw()
+		static void CLOOP_CARG cloopdisposeDispatcher(IDisposable* self) CLOOP_NOEXCEPT
 		{
 			try
 			{
@@ -648,7 +675,7 @@ namespace calc
 			this->cloopVTable = &vTable;
 		}
 
-		static int CLOOP_CARG cloopmultiplyDispatcher(const ICalculator2* self, IStatus* status, int n1, int n2) throw()
+		static int CLOOP_CARG cloopmultiplyDispatcher(const ICalculator2* self, IStatus* status, int n1, int n2) CLOOP_NOEXCEPT
 		{
 			StatusType status2(status);
 
@@ -663,7 +690,7 @@ namespace calc
 			}
 		}
 
-		static void CLOOP_CARG cloopcopyMemoryDispatcher(ICalculator2* self, const ICalculator* calculator) throw()
+		static void CLOOP_CARG cloopcopyMemoryDispatcher(ICalculator2* self, const ICalculator* calculator) CLOOP_NOEXCEPT
 		{
 			try
 			{
@@ -675,7 +702,7 @@ namespace calc
 			}
 		}
 
-		static void CLOOP_CARG cloopcopyMemory2Dispatcher(ICalculator2* self, const int* address) throw()
+		static void CLOOP_CARG cloopcopyMemory2Dispatcher(ICalculator2* self, const int* address) CLOOP_NOEXCEPT
 		{
 			try
 			{
@@ -687,7 +714,7 @@ namespace calc
 			}
 		}
 
-		static int CLOOP_CARG cloopsumDispatcher(const ICalculator* self, IStatus* status, int n1, int n2) throw()
+		static int CLOOP_CARG cloopsumDispatcher(const ICalculator* self, IStatus* status, int n1, int n2) CLOOP_NOEXCEPT
 		{
 			StatusType status2(status);
 
@@ -702,7 +729,7 @@ namespace calc
 			}
 		}
 
-		static int CLOOP_CARG cloopgetMemoryDispatcher(const ICalculator* self) throw()
+		static int CLOOP_CARG cloopgetMemoryDispatcher(const ICalculator* self) CLOOP_NOEXCEPT
 		{
 			try
 			{
@@ -715,7 +742,7 @@ namespace calc
 			}
 		}
 
-		static void CLOOP_CARG cloopsetMemoryDispatcher(ICalculator* self, int n) throw()
+		static void CLOOP_CARG cloopsetMemoryDispatcher(ICalculator* self, int n) CLOOP_NOEXCEPT
 		{
 			try
 			{
@@ -727,7 +754,7 @@ namespace calc
 			}
 		}
 
-		static void CLOOP_CARG cloopsumAndStoreDispatcher(ICalculator* self, IStatus* status, int n1, int n2) throw()
+		static void CLOOP_CARG cloopsumAndStoreDispatcher(ICalculator* self, IStatus* status, int n1, int n2) CLOOP_NOEXCEPT
 		{
 			StatusType status2(status);
 
@@ -741,7 +768,7 @@ namespace calc
 			}
 		}
 
-		static void CLOOP_CARG cloopdisposeDispatcher(IDisposable* self) throw()
+		static void CLOOP_CARG cloopdisposeDispatcher(IDisposable* self) CLOOP_NOEXCEPT
 		{
 			try
 			{
diff --git a/extern/cloop/src/tests/test1/CalcPascalApi.pas b/extern/cloop/src/tests/test1/CalcPascalApi.pas
index 1b202695c1..28b8a583fb 100644
--- a/extern/cloop/src/tests/test1/CalcPascalApi.pas
+++ b/extern/cloop/src/tests/test1/CalcPascalApi.pas
@@ -299,6 +299,7 @@ end;
 
 function StatusImpl_getCodeDispatcher(this: Status): Integer; cdecl;
 begin
+	Result := 0;
 	try
 		Result := StatusImpl(this).getCode();
 	except
@@ -334,6 +335,7 @@ end;
 
 function FactoryImpl_createStatusDispatcher(this: Factory): Status; cdecl;
 begin
+	Result := nil;
 	try
 		Result := FactoryImpl(this).createStatus();
 	except
@@ -343,6 +345,7 @@ end;
 
 function FactoryImpl_createCalculatorDispatcher(this: Factory; status: Status): Calculator; cdecl;
 begin
+	Result := nil;
 	try
 		Result := FactoryImpl(this).createCalculator(status);
 	except
@@ -352,6 +355,7 @@ end;
 
 function FactoryImpl_createCalculator2Dispatcher(this: Factory; status: Status): Calculator2; cdecl;
 begin
+	Result := nil;
 	try
 		Result := FactoryImpl(this).createCalculator2(status);
 	except
@@ -361,6 +365,7 @@ end;
 
 function FactoryImpl_createBrokenCalculatorDispatcher(this: Factory; status: Status): Calculator; cdecl;
 begin
+	Result := nil;
 	try
 		Result := FactoryImpl(this).createBrokenCalculator(status);
 	except
@@ -387,6 +392,7 @@ end;
 
 function CalculatorImpl_sumDispatcher(this: Calculator; status: Status; n1: Integer; n2: Integer): Integer; cdecl;
 begin
+	Result := 0;
 	try
 		Result := CalculatorImpl(this).sum(status, n1, n2);
 	except
@@ -396,6 +402,7 @@ end;
 
 function CalculatorImpl_getMemoryDispatcher(this: Calculator): Integer; cdecl;
 begin
+	Result := 0;
 	try
 		Result := CalculatorImpl(this).getMemory();
 	except
@@ -440,6 +447,7 @@ end;
 
 function Calculator2Impl_sumDispatcher(this: Calculator2; status: Status; n1: Integer; n2: Integer): Integer; cdecl;
 begin
+	Result := 0;
 	try
 		Result := Calculator2Impl(this).sum(status, n1, n2);
 	except
@@ -449,6 +457,7 @@ end;
 
 function Calculator2Impl_getMemoryDispatcher(this: Calculator2): Integer; cdecl;
 begin
+	Result := 0;
 	try
 		Result := Calculator2Impl(this).getMemory();
 	except
@@ -476,6 +485,7 @@ end;
 
 function Calculator2Impl_multiplyDispatcher(this: Calculator2; status: Status; n1: Integer; n2: Integer): Integer; cdecl;
 begin
+	Result := 0;
 	try
 		Result := Calculator2Impl(this).multiply(status, n1, n2);
 	except
diff --git a/src/jrd/CryptoManager.cpp b/src/jrd/CryptoManager.cpp
index 0490a190ec..1bce8f1805 100644
--- a/src/jrd/CryptoManager.cpp
+++ b/src/jrd/CryptoManager.cpp
@@ -823,12 +823,17 @@ namespace Jrd {
 
 	void CryptoManager::blockingAstChangeCryptState()
 	{
-		AsyncContextHolder tdbb(&dbb, FB_FUNCTION);
-
-		if (stateLock->lck_physical != CRYPT_CHANGE && stateLock->lck_physical != CRYPT_INIT)
+		try
 		{
-			sync.ast(tdbb);
+			AsyncContextHolder tdbb(&dbb, FB_FUNCTION);
+
+			if (stateLock->lck_physical != CRYPT_CHANGE && stateLock->lck_physical != CRYPT_INIT)
+			{
+				sync.ast(tdbb);
+			}
 		}
+		catch (const Exception&)
+		{ }
 	}
 
 	void CryptoManager::doOnAst(thread_db* tdbb)
diff --git a/src/jrd/tpc.cpp b/src/jrd/tpc.cpp
index f1b059b8eb..c0960a5d5a 100644
--- a/src/jrd/tpc.cpp
+++ b/src/jrd/tpc.cpp
@@ -705,28 +705,33 @@ int TipCache::tpc_block_blocking_ast(void* arg)
 {
 	StatusBlockData* data = static_cast<StatusBlockData*>(arg);
 
-	Database* dbb = data->existenceLock.lck_dbb;
-	AsyncContextHolder tdbb(dbb, FB_FUNCTION);
-
-	// Should we try to process AST?
-	if (!data->acceptAst)
-		return 0;
-
-	TipCache* cache = data->cache;
-	TraNumber oldest =
-		cache->m_tpcHeader->getHeader()->oldest_transaction.load(std::memory_order_relaxed);
-
-	// Is data block really old?
-	if (data->blockNumber >= oldest / cache->m_transactionsPerBlock)
-		return 0;
-
-	// Release shared memory
-	if (data->memory)
+	try
 	{
-		delete data->memory;
-		data->memory = NULL;
+		Database* dbb = data->existenceLock.lck_dbb;
+		AsyncContextHolder tdbb(dbb, FB_FUNCTION);
+
+		// Should we try to process AST?
+		if (!data->acceptAst)
+			return 0;
+
+		TipCache* cache = data->cache;
+		TraNumber oldest =
+			cache->m_tpcHeader->getHeader()->oldest_transaction.load(std::memory_order_relaxed);
+
+		// Is data block really old?
+		if (data->blockNumber >= oldest / cache->m_transactionsPerBlock)
+			return 0;
+
+		// Release shared memory
+		if (data->memory)
+		{
+			delete data->memory;
+			data->memory = NULL;
+		}
+		LCK_release(tdbb, &data->existenceLock);
 	}
-	LCK_release(tdbb, &data->existenceLock);
+	catch (const Exception&)
+	{ }
 
 	return 0;
 }
diff --git a/src/lock/lock.cpp b/src/lock/lock.cpp
index 267368cd41..59fab14dd6 100644
--- a/src/lock/lock.cpp
+++ b/src/lock/lock.cpp
@@ -1398,7 +1398,19 @@ void LockManager::blocking_action(thread_db* tdbb, SRQ_PTR blocking_owner_offset
 			{ // checkout scope
 				LockTableCheckout checkout(this, FB_FUNCTION);
 				EngineCheckout cout(tdbb, FB_FUNCTION, EngineCheckout::UNNECESSARY);
-				(*routine)(arg);
+
+				try
+				{
+					(*routine)(arg);
+				}
+				catch (const Exception& ex)
+				{
+					iscLogException("Exception from AST routine - this should never happen", ex);
+				}
+				catch (...)
+				{
+					gds__log("Unknown C++ exception from AST routine - this should never happen");
+				}
 			}
 
 			owner = (own*) SRQ_ABS_PTR(blocking_owner_offset);