diff --git a/ipmi.cpp b/ipmi.cpp
index fb5f120..e2e0fef 100644
--- a/ipmi.cpp
+++ b/ipmi.cpp
@@ -105,7 +105,7 @@
     std::string blobId = mgr->getBlobId(request.blobIdx);
     if (blobId == "")
     {
-        return IPMI_CC_INVALID;
+        return IPMI_CC_INVALID_FIELD_REQUEST;
     }
 
     /* TODO(venture): Need to do a hard-code check against the maximum
@@ -130,13 +130,13 @@
         request->blobId, (requestLen - sizeof(struct BmcBlobOpenTx)));
     if (path.empty())
     {
-        return IPMI_CC_INVALID;
+        return IPMI_CC_REQ_DATA_LEN_INVALID;
     }
 
     /* Attempt to open. */
     if (!mgr->open(request->flags, path, &session))
     {
-        return IPMI_CC_INVALID;
+        return IPMI_CC_UNSPECIFIED_ERROR;
     }
 
     struct BmcBlobOpenRx reply;
@@ -158,7 +158,7 @@
     /* Attempt to close. */
     if (!mgr->close(request.sessionId))
     {
-        return IPMI_CC_INVALID;
+        return IPMI_CC_UNSPECIFIED_ERROR;
     }
 
     (*dataLen) = 0;
@@ -175,13 +175,13 @@
         request->blobId, (requestLen - sizeof(struct BmcBlobDeleteTx)));
     if (path.empty())
     {
-        return IPMI_CC_INVALID;
+        return IPMI_CC_REQ_DATA_LEN_INVALID;
     }
 
     /* Attempt to delete. */
     if (!mgr->deleteBlob(path))
     {
-        return IPMI_CC_INVALID;
+        return IPMI_CC_UNSPECIFIED_ERROR;
     }
 
     (*dataLen) = 0;
@@ -220,14 +220,14 @@
         request->blobId, (requestLen - sizeof(struct BmcBlobStatTx)));
     if (path.empty())
     {
-        return IPMI_CC_INVALID;
+        return IPMI_CC_REQ_DATA_LEN_INVALID;
     }
 
     /* Attempt to stat. */
     struct BlobMeta meta;
     if (!mgr->stat(path, &meta))
     {
-        return IPMI_CC_INVALID;
+        return IPMI_CC_UNSPECIFIED_ERROR;
     }
 
     return returnStatBlob(&meta, replyCmdBuf, dataLen);
@@ -244,7 +244,7 @@
 
     if (!mgr->stat(request.sessionId, &meta))
     {
-        return IPMI_CC_INVALID;
+        return IPMI_CC_UNSPECIFIED_ERROR;
     }
 
     return returnStatBlob(&meta, replyCmdBuf, dataLen);
@@ -259,7 +259,7 @@
     /* Sanity check the commitDataLen */
     if (request->commitDataLen > (requestLen - sizeof(struct BmcBlobCommitTx)))
     {
-        return IPMI_CC_INVALID;
+        return IPMI_CC_REQ_DATA_LEN_INVALID;
     }
 
     std::vector<uint8_t> data(request->commitDataLen);
@@ -267,7 +267,7 @@
 
     if (!mgr->commit(request->sessionId, data))
     {
-        return IPMI_CC_INVALID;
+        return IPMI_CC_UNSPECIFIED_ERROR;
     }
 
     (*dataLen) = 0;
@@ -317,7 +317,7 @@
     /* Attempt to write the bytes. */
     if (!mgr->write(request->sessionId, request->offset, data))
     {
-        return IPMI_CC_INVALID;
+        return IPMI_CC_UNSPECIFIED_ERROR;
     }
 
     return IPMI_CC_OK;
@@ -342,7 +342,7 @@
     /* Attempt to write the bytes. */
     if (!mgr->writeMeta(request.sessionId, request.offset, data))
     {
-        return IPMI_CC_INVALID;
+        return IPMI_CC_UNSPECIFIED_ERROR;
     }
 
     return IPMI_CC_OK;
diff --git a/main.cpp b/main.cpp
index dda9dec..4328567 100644
--- a/main.cpp
+++ b/main.cpp
@@ -47,15 +47,17 @@
      */
     if ((*dataLen) < 1)
     {
-        return IPMI_CC_INVALID;
+        return IPMI_CC_REQ_DATA_LEN_INVALID;
     }
 
+    /* on failure rc is set to the corresponding IPMI error. */
+    ipmi_ret_t rc = IPMI_CC_OK;
     Crc16 crc;
     IpmiBlobHandler command =
-        validateBlobCommand(&crc, reqBuf, replyCmdBuf, dataLen);
+        validateBlobCommand(&crc, reqBuf, replyCmdBuf, dataLen, &rc);
     if (command == nullptr)
     {
-        return IPMI_CC_INVALID;
+        return rc;
     }
 
     return processBlobCommand(command, getBlobManager(), &crc, reqBuf,
diff --git a/process.cpp b/process.cpp
index 245da69..7e6410d 100644
--- a/process.cpp
+++ b/process.cpp
@@ -48,7 +48,8 @@
 };
 
 IpmiBlobHandler validateBlobCommand(CrcInterface* crc, const uint8_t* reqBuf,
-                                    uint8_t* replyCmdBuf, size_t* dataLen)
+                                    uint8_t* replyCmdBuf, size_t* dataLen,
+                                    ipmi_ret_t* code)
 {
     size_t requestLength = (*dataLen);
     /* We know dataLen is at least 1 already */
@@ -57,6 +58,7 @@
     /* Validate it's at least well-formed. */
     if (!validateRequestLength(command, requestLength))
     {
+        *code = IPMI_CC_REQ_DATA_LEN_INVALID;
         return nullptr;
     }
 
@@ -66,6 +68,7 @@
         /* Verify the request includes: command, crc16, data */
         if (requestLength < sizeof(struct BmcRx))
         {
+            *code = IPMI_CC_REQ_DATA_LEN_INVALID;
             return nullptr;
         }
 
@@ -91,6 +94,7 @@
         /* Crc expected but didn't match. */
         if (crcValue != crc->get())
         {
+            *code = IPMI_CC_UNSPECIFIED_ERROR;
             return nullptr;
         }
     }
@@ -99,6 +103,7 @@
     auto found = handlers.find(command);
     if (found == handlers.end())
     {
+        *code = IPMI_CC_INVALID_FIELD_REQUEST;
         return nullptr;
     }
 
@@ -126,7 +131,7 @@
     /* The response, if it has one byte, has three, to include the crc16. */
     if (replyLength < (sizeof(uint16_t) + 1))
     {
-        return IPMI_CC_INVALID;
+        return IPMI_CC_UNSPECIFIED_ERROR;
     }
 
     /* The command, whatever it was, replied, so let's set the CRC. */
diff --git a/process.hpp b/process.hpp
index 8f874dc..0e377bc 100644
--- a/process.hpp
+++ b/process.hpp
@@ -22,10 +22,12 @@
  * @param[in,out] replyCmdBuf - a pointer to the ipmi reply packet buffer.
  * @param[in,out] dataLen - initially the request length, set to reply length
  *                          on return.
- * @return the ipmi command handler.
+ * @param[out] code - set to the IPMI error on failure, otherwise unset.
+ * @return the ipmi command handler, or nullptr on failure.
  */
 IpmiBlobHandler validateBlobCommand(CrcInterface* crc, const uint8_t* reqBuf,
-                                    uint8_t* replyCmdBuf, size_t* dataLen);
+                                    uint8_t* replyCmdBuf, size_t* dataLen,
+                                    ipmi_ret_t* code);
 
 /**
  * Call the IPMI command and process the result, including running the CRC
diff --git a/test/ipmi_close_unittest.cpp b/test/ipmi_close_unittest.cpp
index f315ea0..edfddca 100644
--- a/test/ipmi_close_unittest.cpp
+++ b/test/ipmi_close_unittest.cpp
@@ -38,7 +38,8 @@
     std::memcpy(request, &req, sizeof(req));
 
     EXPECT_CALL(mgr, close(sessionId)).WillOnce(Return(false));
-    EXPECT_EQ(IPMI_CC_INVALID, closeBlob(&mgr, request, reply, &dataLen));
+    EXPECT_EQ(IPMI_CC_UNSPECIFIED_ERROR,
+              closeBlob(&mgr, request, reply, &dataLen));
 }
 
 TEST(BlobCloseTest, BlobClosedReturnsSuccess)
diff --git a/test/ipmi_commit_unittest.cpp b/test/ipmi_commit_unittest.cpp
index 34ff10d..30f78bf 100644
--- a/test/ipmi_commit_unittest.cpp
+++ b/test/ipmi_commit_unittest.cpp
@@ -35,7 +35,8 @@
 
     dataLen = sizeof(struct BmcBlobCommitTx);
 
-    EXPECT_EQ(IPMI_CC_INVALID, commitBlob(&mgr, request, reply, &dataLen));
+    EXPECT_EQ(IPMI_CC_REQ_DATA_LEN_INVALID,
+              commitBlob(&mgr, request, reply, &dataLen));
 }
 
 TEST(BlobCommitTest, ValidCommitNoDataHandlerRejectsReturnsFailure)
@@ -57,7 +58,8 @@
 
     EXPECT_CALL(mgr, commit(req->sessionId, _)).WillOnce(Return(false));
 
-    EXPECT_EQ(IPMI_CC_INVALID, commitBlob(&mgr, request, reply, &dataLen));
+    EXPECT_EQ(IPMI_CC_UNSPECIFIED_ERROR,
+              commitBlob(&mgr, request, reply, &dataLen));
 }
 
 TEST(BlobCommitTest, ValidCommitNoDataHandlerAcceptsReturnsSuccess)
diff --git a/test/ipmi_delete_unittest.cpp b/test/ipmi_delete_unittest.cpp
index 409635d..6985eb1 100644
--- a/test/ipmi_delete_unittest.cpp
+++ b/test/ipmi_delete_unittest.cpp
@@ -36,7 +36,8 @@
 
     dataLen = sizeof(struct BmcBlobDeleteTx) + blobId.length();
 
-    EXPECT_EQ(IPMI_CC_INVALID, deleteBlob(&mgr, request, reply, &dataLen));
+    EXPECT_EQ(IPMI_CC_REQ_DATA_LEN_INVALID,
+              deleteBlob(&mgr, request, reply, &dataLen));
 }
 
 TEST(BlobDeleteTest, RequestRejectedReturnsFailure)
@@ -60,7 +61,8 @@
 
     EXPECT_CALL(mgr, deleteBlob(StrEq(blobId))).WillOnce(Return(false));
 
-    EXPECT_EQ(IPMI_CC_INVALID, deleteBlob(&mgr, request, reply, &dataLen));
+    EXPECT_EQ(IPMI_CC_UNSPECIFIED_ERROR,
+              deleteBlob(&mgr, request, reply, &dataLen));
 }
 
 TEST(BlobDeleteTest, BlobDeleteReturnsOk)
diff --git a/test/ipmi_enumerate_unittest.cpp b/test/ipmi_enumerate_unittest.cpp
index 041a8cb..184c686 100644
--- a/test/ipmi_enumerate_unittest.cpp
+++ b/test/ipmi_enumerate_unittest.cpp
@@ -31,7 +31,8 @@
 
     EXPECT_CALL(mgr, getBlobId(req.blobIdx)).WillOnce(Return(""));
 
-    EXPECT_EQ(IPMI_CC_INVALID, enumerateBlob(&mgr, request, reply, &dataLen));
+    EXPECT_EQ(IPMI_CC_INVALID_FIELD_REQUEST,
+              enumerateBlob(&mgr, request, reply, &dataLen));
 }
 
 TEST(BlobEnumerateTest, BoringRequestByIdAndReceive)
diff --git a/test/ipmi_open_unittest.cpp b/test/ipmi_open_unittest.cpp
index 523025d..704c144 100644
--- a/test/ipmi_open_unittest.cpp
+++ b/test/ipmi_open_unittest.cpp
@@ -39,7 +39,8 @@
 
     dataLen = sizeof(struct BmcBlobOpenTx) + blobId.length();
 
-    EXPECT_EQ(IPMI_CC_INVALID, openBlob(&mgr, request, reply, &dataLen));
+    EXPECT_EQ(IPMI_CC_REQ_DATA_LEN_INVALID,
+              openBlob(&mgr, request, reply, &dataLen));
 }
 
 TEST(BlobOpenTest, RequestRejectedReturnsFailure)
@@ -65,7 +66,8 @@
     EXPECT_CALL(mgr, open(req->flags, StrEq(blobId), _))
         .WillOnce(Return(false));
 
-    EXPECT_EQ(IPMI_CC_INVALID, openBlob(&mgr, request, reply, &dataLen));
+    EXPECT_EQ(IPMI_CC_UNSPECIFIED_ERROR,
+              openBlob(&mgr, request, reply, &dataLen));
 }
 
 TEST(BlobOpenTest, BlobOpenReturnsOk)
diff --git a/test/ipmi_sessionstat_unittest.cpp b/test/ipmi_sessionstat_unittest.cpp
index 70c36ec..a71252c 100644
--- a/test/ipmi_sessionstat_unittest.cpp
+++ b/test/ipmi_sessionstat_unittest.cpp
@@ -37,7 +37,8 @@
                           Matcher<struct BlobMeta*>(_)))
         .WillOnce(Return(false));
 
-    EXPECT_EQ(IPMI_CC_INVALID, sessionStatBlob(&mgr, request, reply, &dataLen));
+    EXPECT_EQ(IPMI_CC_UNSPECIFIED_ERROR,
+              sessionStatBlob(&mgr, request, reply, &dataLen));
 }
 
 TEST(BlobSessionStatTest, RequestSucceedsNoMetadata)
diff --git a/test/ipmi_stat_unittest.cpp b/test/ipmi_stat_unittest.cpp
index 75f90c4..e7ff277 100644
--- a/test/ipmi_stat_unittest.cpp
+++ b/test/ipmi_stat_unittest.cpp
@@ -39,7 +39,8 @@
 
     dataLen = sizeof(struct BmcBlobStatTx) + blobId.length();
 
-    EXPECT_EQ(IPMI_CC_INVALID, statBlob(&mgr, request, reply, &dataLen));
+    EXPECT_EQ(IPMI_CC_REQ_DATA_LEN_INVALID,
+              statBlob(&mgr, request, reply, &dataLen));
 }
 
 TEST(BlobStatTest, RequestRejectedReturnsFailure)
@@ -65,7 +66,8 @@
                           Matcher<struct BlobMeta*>(_)))
         .WillOnce(Return(false));
 
-    EXPECT_EQ(IPMI_CC_INVALID, statBlob(&mgr, request, reply, &dataLen));
+    EXPECT_EQ(IPMI_CC_UNSPECIFIED_ERROR,
+              statBlob(&mgr, request, reply, &dataLen));
 }
 
 TEST(BlobStatTest, RequestSucceedsNoMetadata)
diff --git a/test/ipmi_write_unittest.cpp b/test/ipmi_write_unittest.cpp
index 7b5e45f..99615af 100644
--- a/test/ipmi_write_unittest.cpp
+++ b/test/ipmi_write_unittest.cpp
@@ -40,7 +40,8 @@
                       ElementsAreArray(expectedBytes, sizeof(expectedBytes))))
         .WillOnce(Return(false));
 
-    EXPECT_EQ(IPMI_CC_INVALID, writeBlob(&mgr, request, reply, &dataLen));
+    EXPECT_EQ(IPMI_CC_UNSPECIFIED_ERROR,
+              writeBlob(&mgr, request, reply, &dataLen));
 }
 
 TEST(BlobWriteTest, ManagerReturnsTrueWriteSucceeds)
diff --git a/test/ipmi_writemeta_unittest.cpp b/test/ipmi_writemeta_unittest.cpp
index 2dfbe59..2d63452 100644
--- a/test/ipmi_writemeta_unittest.cpp
+++ b/test/ipmi_writemeta_unittest.cpp
@@ -39,7 +39,8 @@
                        ElementsAreArray(expectedBytes, sizeof(expectedBytes))))
         .WillOnce(Return(false));
 
-    EXPECT_EQ(IPMI_CC_INVALID, writeMeta(&mgr, request, reply, &dataLen));
+    EXPECT_EQ(IPMI_CC_UNSPECIFIED_ERROR,
+              writeMeta(&mgr, request, reply, &dataLen));
 }
 
 TEST(BlobWriteMetaTest, ManagerReturnsTrueWriteSucceeds)
diff --git a/test/process_unittest.cpp b/test/process_unittest.cpp
index 63e6f5e..4f8c9a6 100644
--- a/test/process_unittest.cpp
+++ b/test/process_unittest.cpp
@@ -57,8 +57,11 @@
 
     request[0] = 0xff;         // There is no command 0xff.
     dataLen = sizeof(uint8_t); // There is no payload for CRC.
+    ipmi_ret_t rc;
 
-    EXPECT_EQ(nullptr, validateBlobCommand(&crc, request, reply, &dataLen));
+    EXPECT_EQ(nullptr,
+              validateBlobCommand(&crc, request, reply, &dataLen, &rc));
+    EXPECT_EQ(IPMI_CC_INVALID_FIELD_REQUEST, rc);
 }
 
 TEST(ValidateBlobCommandTest, ValidCommandWithoutPayload)
@@ -72,8 +75,10 @@
 
     request[0] = BlobOEMCommands::bmcBlobGetCount;
     dataLen = sizeof(uint8_t); // There is no payload for CRC.
+    ipmi_ret_t rc;
 
-    IpmiBlobHandler res = validateBlobCommand(&crc, request, reply, &dataLen);
+    IpmiBlobHandler res =
+        validateBlobCommand(&crc, request, reply, &dataLen, &rc);
     EXPECT_FALSE(res == nullptr);
     EqualFunctions(getBlobCount, res);
 }
@@ -91,8 +96,11 @@
     request[0] = BlobOEMCommands::bmcBlobGetCount;
     dataLen = sizeof(uint8_t) + sizeof(uint16_t);
     // There is a payload, but there are insufficient bytes.
+    ipmi_ret_t rc;
 
-    EXPECT_EQ(nullptr, validateBlobCommand(&crc, request, reply, &dataLen));
+    EXPECT_EQ(nullptr,
+              validateBlobCommand(&crc, request, reply, &dataLen, &rc));
+    EXPECT_EQ(IPMI_CC_REQ_DATA_LEN_INVALID, rc);
 }
 
 TEST(ValidateBlobCommandTest, WithPayloadAndInvalidCrc)
@@ -125,7 +133,11 @@
         }));
     EXPECT_CALL(crc, get()).WillOnce(Return(0x1234));
 
-    EXPECT_EQ(nullptr, validateBlobCommand(&crc, request, reply, &dataLen));
+    ipmi_ret_t rc;
+
+    EXPECT_EQ(nullptr,
+              validateBlobCommand(&crc, request, reply, &dataLen, &rc));
+    EXPECT_EQ(IPMI_CC_UNSPECIFIED_ERROR, rc);
 }
 
 TEST(ValidateBlobCommandTest, WithPayloadAndValidCrc)
@@ -158,7 +170,10 @@
         }));
     EXPECT_CALL(crc, get()).WillOnce(Return(0x3412));
 
-    IpmiBlobHandler res = validateBlobCommand(&crc, request, reply, &dataLen);
+    ipmi_ret_t rc;
+
+    IpmiBlobHandler res =
+        validateBlobCommand(&crc, request, reply, &dataLen, &rc);
     EXPECT_FALSE(res == nullptr);
     EqualFunctions(writeBlob, res);
 }
@@ -181,8 +196,10 @@
     uint8_t reply[MAX_IPMI_BUFFER] = {0};
 
     dataLen = sizeof(request);
+    ipmi_ret_t rc;
 
-    IpmiBlobHandler res = validateBlobCommand(&crc, request, reply, &dataLen);
+    IpmiBlobHandler res =
+        validateBlobCommand(&crc, request, reply, &dataLen, &rc);
     EXPECT_FALSE(res == nullptr);
     EqualFunctions(openBlob, res);
 }
@@ -250,7 +267,7 @@
 
     dataLen = sizeof(request);
 
-    EXPECT_EQ(IPMI_CC_INVALID,
+    EXPECT_EQ(IPMI_CC_UNSPECIFIED_ERROR,
               processBlobCommand(h, &manager, &crc, request, reply, &dataLen));
 }