diff --git a/Source/7zip/7zip/Compress/LZ/BinTree/BinTreeMain.h b/Source/7zip/7zip/Compress/LZ/BinTree/BinTreeMain.h
index fc568bc7..04f88989 100644
--- a/Source/7zip/7zip/Compress/LZ/BinTree/BinTreeMain.h
+++ b/Source/7zip/7zip/Compress/LZ/BinTree/BinTreeMain.h
@@ -102,10 +102,10 @@ HRESULT CInTree::Create(UINT32 sizeHistory, UINT32 keepAddBufferBefore,
     #ifdef WIN32
     _son = (CPair *)::VirtualAlloc(0, (_cyclicBufferSize + 1) * sizeof(CPair), MEM_COMMIT, PAGE_READWRITE);
     if (_son == 0)
-      throw 1; // CNewException();
+      throw CMemoryException();
     _hash = (CIndex *)::VirtualAlloc(0, (size + 1) * sizeof(CIndex), MEM_COMMIT, PAGE_READWRITE);
     if (_hash == 0)
-      throw 1; // CNewException();
+      throw CMemoryException();
     #else
     _son = new CPair[_cyclicBufferSize + 1];
     _hash = new CIndex[size + 1];
diff --git a/Source/7zip/Common/Defs.h b/Source/7zip/Common/Defs.h
index bfaaa6c9..35837d0d 100644
--- a/Source/7zip/Common/Defs.h
+++ b/Source/7zip/Common/Defs.h
@@ -19,4 +19,10 @@ inline int BoolToInt(bool value)
 inline bool IntToBool(int value)
   { return (value != 0); }
 
+class CMemoryException
+{
+public:
+  CMemoryException() {}
+};
+
 #endif
diff --git a/Source/build.cpp b/Source/build.cpp
index a1d45798..93f0f494 100644
--- a/Source/build.cpp
+++ b/Source/build.cpp
@@ -785,7 +785,7 @@ int CEXEBuild::add_db_data(IMMap *map) // returns offset
       n = compressor->Init(build_compress_level);
     if (n != C_OK)
     {
-      ERROR_MSG("Internal compiler error #12345: deflateInit() failed(%d).\n", n);
+      ERROR_MSG("Internal compiler error #12345: deflateInit() failed(%d - %s).\n", n, compressor->GetErrStr(n));
       extern void quit(); quit();
     }
 
@@ -801,7 +801,7 @@ int CEXEBuild::add_db_data(IMMap *map) // returns offset
       compressor->SetNextOut((char *) db->get(st + sizeof(int) + bufferlen - avail_out, out_len), out_len);
       if ((ret = compressor->Compress(0)) < 0)
       {
-        ERROR_MSG("Error: add_db_data() - compress() failed - %d\n", ret);
+        ERROR_MSG("Error: add_db_data() - compress() failed(%d - %s)\n", ret, compressor->GetErrStr(ret));
         return -1;
       }
       map->release();
@@ -832,7 +832,7 @@ int CEXEBuild::add_db_data(IMMap *map) // returns offset
         compressor->SetNextOut(out, out_len);
         if ((ret = compressor->Compress(C_FINISH)) < 0)
         {
-          ERROR_MSG("Error: add_db_data() - compress() failed - %d\n", ret);
+          ERROR_MSG("Error: add_db_data() - compress() failed(%d - %s)\n", ret, compressor->GetErrStr(ret));
           return -1;
         }
 
@@ -928,7 +928,7 @@ int CEXEBuild::add_data(const char *data, int length, IGrowBuf *dblock) // retur
       n = compressor->Init(build_compress_level);
     if (n != C_OK)
     {
-      ERROR_MSG("Internal compiler error #12345: deflateInit() failed(%d).\n",n);
+      ERROR_MSG("Internal compiler error #12345: deflateInit() failed(%d - %s).\n", n, compressor->GetErrStr(n));
       extern void quit(); quit();
     }
 
@@ -2432,7 +2432,7 @@ int CEXEBuild::write_output(void)
       n = compressor->Init(build_compress_level);
     if (n != C_OK)
     {
-      ERROR_MSG("Internal compiler error #12345: deflateInit() failed(%d).\n", n);
+      ERROR_MSG("Internal compiler error #12345: deflateInit() failed(%d - %s).\n", n, compressor->GetErrStr(n));
       return PS_ERROR;
     }
   }
@@ -2733,7 +2733,7 @@ int CEXEBuild::deflateToFile(FILE *fp, char *buf, int len) // len==0 to flush
     int ret=compressor->Compress(flush);
     if (ret<0 && (ret!=-1 || !flush))
     {
-      ERROR_MSG("Error: deflateToFile: deflate()=%d\n",ret);
+      ERROR_MSG("Error: deflateToFile: deflate() failed(%d - %s)\n", ret, compressor->GetErrStr(ret));
       return 1;
     }
     int l=compressor->GetNextOut()-obuf;
@@ -2863,7 +2863,7 @@ int CEXEBuild::uninstall_generate()
           n = compressor->Init(build_compress_level);
         if (n != C_OK)
         {
-          ERROR_MSG("Internal compiler error #12345: deflateInit() failed(%d).\n", n);
+          ERROR_MSG("Internal compiler error #12345: deflateInit() failed(%d - %s).\n", n, compressor->GetErrStr(n));
           extern void quit(); quit();
         }
 
diff --git a/Source/cbzip2.h b/Source/cbzip2.h
index ae19debd..8437179c 100644
--- a/Source/cbzip2.h
+++ b/Source/cbzip2.h
@@ -53,6 +53,22 @@ class CBzip2 : public ICompressor {
       return "bzip2";
     }
 
+    const char* GetErrStr(int err) {
+      switch (err)
+      {
+      case BZ_SEQUENCE_ERROR:
+        return "sequence error - bad call";
+      case BZ_PARAM_ERROR:
+        return "parameter error - bad call";
+      case BZ_MEM_ERROR:
+        return "not enough memory";
+      case BZ_CONFIG_ERROR:
+        return "config error";
+      default:
+        return "unknown error";
+      }
+    }
+
   private:
     bz_stream *stream;
     int last_ret;
diff --git a/Source/clzma.h b/Source/clzma.h
index d4fe0b9c..b394eb31 100644
--- a/Source/clzma.h
+++ b/Source/clzma.h
@@ -5,6 +5,7 @@
 #include "7zip/7zip/IStream.h"
 #include "7zip/7zip/Compress/LZMA/LZMAEncoder.h"
 #include "7zip/Common/MyCom.h"
+#include "7zip/Common/Defs.h"
 
 // implemented in build.cpp - simply calls CompressReal
 #ifdef _WIN32
@@ -13,6 +14,12 @@ DWORD WINAPI lzmaCompressThread(LPVOID lpParameter);
 void *lzmaCompressThread(void *arg);
 #endif
 
+#define LZMA_BAD_CALL -1
+#define LZMA_INIT_ERROR -2
+#define LZMA_THREAD_ERROR -3
+#define LZMA_IO_ERROR -4
+#define LZMA_MEM_ERROR -5
+
 class CLZMA:
   public ICompressor,
   public ISequentialInStream,
@@ -169,6 +176,12 @@ public:
 
     compressor_finished = FALSE;
     finish = FALSE;
+    res = C_OK;
+
+    if (!hNeedIOEvent || !hIOReadyEvent)
+    {
+      return LZMA_INIT_ERROR;
+    }
 
     ResetEvent(hNeedIOEvent);
     ResetEvent(hIOReadyEvent);
@@ -193,7 +206,7 @@ public:
     props[2].vt = VT_UI4;
     props[2].ulVal = 64;
     if (_encoder->SetCoderProperties(propdIDs, props, kNumProps) != 0)
-      return -1;
+      return LZMA_INIT_ERROR;
     return _encoder->SetStreams(this, this, 0, 0);
   }
 
@@ -246,7 +259,8 @@ public:
           INT32 finished;
           if (_encoder->CodeOneBlock(&inSize, &outSize, &finished))
           {
-            res = -2;
+            if (res != C_OK)
+              res = LZMA_IO_ERROR;
             break;
           }
           if (finished)
@@ -258,12 +272,16 @@ public:
       }
       else
       {
-        res = -2;
+        res = LZMA_IO_ERROR;
       }
     }
+    catch (CMemoryException)
+    {
+      res = LZMA_MEM_ERROR;
+    }
     catch (...)
     {
-      res = -3;
+      res = LZMA_IO_ERROR;
     }
 
     compressor_finished = TRUE;
@@ -279,7 +297,7 @@ public:
       if (flush)
         return C_OK;
       else
-        return -1;
+        return LZMA_BAD_CALL;
     }
 
     finish = flush;
@@ -294,7 +312,7 @@ public:
 #else
       if (pthread_create(&hCompressionThread, NULL, lzmaCompressThread, (LPVOID) this))
 #endif
-        return -2;
+        return LZMA_INIT_ERROR;
     }
     else
     {
@@ -307,7 +325,7 @@ public:
       // thread ended or WaitForMultipleObjects failed
       compressor_finished = TRUE;
       SetEvent(hIOReadyEvent);
-      return -4;
+      return LZMA_THREAD_ERROR;
     }
 
     if (compressor_finished)
@@ -322,7 +340,10 @@ public:
   {
     SetEvent(hNeedIOEvent);
     if (WaitForSingleObject(hIOReadyEvent, INFINITE) != WAIT_OBJECT_0)
+    {
       compressor_finished = TRUE;
+      res = LZMA_THREAD_ERROR;
+    }
   }
 
   STDMETHOD(Read)(void *data, UINT32 size, UINT32 *processedSize)
@@ -411,6 +432,24 @@ public:
   virtual unsigned int GetAvailIn() { return avail_in; }
   virtual unsigned int GetAvailOut() { return avail_out; }
   const char *GetName() { return "lzma"; }
+
+  const char* GetErrStr(int err) {
+    switch (err)
+    {
+    case LZMA_BAD_CALL:
+      return "bad call";
+    case LZMA_INIT_ERROR:
+      return "initialization failed";
+    case LZMA_THREAD_ERROR:
+      return "thread synchronization error";
+    case LZMA_IO_ERROR:
+      return "input/output error";
+    case LZMA_MEM_ERROR:
+      return "not enough memory";
+    default:
+      return "unknown error";
+    }
+  }
 };
 
 #endif
diff --git a/Source/compressor.h b/Source/compressor.h
index 971e37ed..e01e0d5e 100644
--- a/Source/compressor.h
+++ b/Source/compressor.h
@@ -19,6 +19,8 @@ class ICompressor {
     virtual unsigned int GetAvailOut() = 0;
 
     virtual const char* GetName() = 0;
+
+    virtual const char* GetErrStr(int err) = 0;
 };
 
 #endif
diff --git a/Source/czlib.h b/Source/czlib.h
index 53df9bf2..c0b6cd51 100644
--- a/Source/czlib.h
+++ b/Source/czlib.h
@@ -48,6 +48,24 @@ class CZlib : public ICompressor {
       return "zlib";
     }
 
+    const char* GetErrStr(int err) {
+      switch (err)
+      {
+      case Z_STREAM_ERROR:
+        return "invalid stream - bad call";
+      case Z_DATA_ERROR:
+        return "data error";
+      case Z_MEM_ERROR:
+        return "not enough memory";
+      case Z_BUF_ERROR:
+        return "buffer error - bad call";
+      case Z_VERSION_ERROR:
+        return "version error";
+      default:
+        return "unknown error";
+      }
+    }
+
   private:
     z_stream *stream;
 };