diff --git a/core/services/ocr2/plugins/ocr2keeper/evm21/streams_lookup.go b/core/services/ocr2/plugins/ocr2keeper/evm21/streams_lookup.go
index 2155b383002..6c1789de9c4 100644
--- a/core/services/ocr2/plugins/ocr2keeper/evm21/streams_lookup.go
+++ b/core/services/ocr2/plugins/ocr2keeper/evm21/streams_lookup.go
@@ -66,10 +66,10 @@ type MercuryV03Response struct {
 }
 
 type MercuryV03Report struct {
-	FeedID                []byte `json:"feedID"` // feed id in hex
+	FeedID                string `json:"feedID"` // feed id in hex encoded
 	ValidFromTimestamp    uint32 `json:"validFromTimestamp"`
 	ObservationsTimestamp uint32 `json:"observationsTimestamp"`
-	FullReport            []byte `json:"fullReport"` // the actual mercury report of this feed, can be sent to verifier
+	FullReport            string `json:"fullReport"` // the actual hex encoded mercury report of this feed, can be sent to verifier
 }
 
 type MercuryData struct {
@@ -528,6 +528,7 @@ func (r *EvmRegistry) multiFeedsRequest(ctx context.Context, ch chan<- MercuryDa
 			} else if resp.StatusCode == 420 {
 				// in 0.3, this will happen when missing/malformed query args, missing or bad required headers, non-existent feeds, or no permissions for feeds
 				retryable = false
+				state = encoding.InvalidMercuryRequest
 				return fmt.Errorf("at timestamp %s upkeep %s received status code %d from mercury v0.3, most likely this is caused by missing/malformed query args, missing or bad required headers, non-existent feeds, or no permissions for feeds", sl.time.String(), sl.upkeepId.String(), resp.StatusCode)
 			} else if resp.StatusCode != http.StatusOK {
 				retryable = false
@@ -549,13 +550,21 @@ func (r *EvmRegistry) multiFeedsRequest(ctx context.Context, ch chan<- MercuryDa
 			// hence, retry in this case. retry will help when we send a very new timestamp and reports are not yet generated
 			if len(response.Reports) != len(sl.feeds) {
 				// TODO: AUTO-5044: calculate what reports are missing and log a warning
+				lggr.Warnf("at timestamp %s upkeep %s mercury v0.3 server retruned 200 status with %d reports while we requested %d feeds, treating as 404 (not found) and retrying", sl.time.String(), sl.upkeepId.String(), len(response.Reports), len(sl.feeds))
 				retryable = true
 				state = encoding.MercuryFlakyFailure
 				return fmt.Errorf("%d", http.StatusNotFound)
 			}
 			var reportBytes [][]byte
 			for _, rsp := range response.Reports {
-				reportBytes = append(reportBytes, rsp.FullReport)
+				b, err := hexutil.Decode(rsp.FullReport)
+				if err != nil {
+					lggr.Warnf("at timestamp %s upkeep %s failed to decode reportBlob %s: %v", sl.time.String(), sl.upkeepId.String(), rsp.FullReport, err)
+					retryable = false
+					state = encoding.InvalidMercuryResponse
+					return err
+				}
+				reportBytes = append(reportBytes, b)
 			}
 			ch <- MercuryData{
 				Index:     0,
diff --git a/core/services/ocr2/plugins/ocr2keeper/evm21/streams_lookup_test.go b/core/services/ocr2/plugins/ocr2keeper/evm21/streams_lookup_test.go
index 42aeecb64f6..f59cec18c1e 100644
--- a/core/services/ocr2/plugins/ocr2keeper/evm21/streams_lookup_test.go
+++ b/core/services/ocr2/plugins/ocr2keeper/evm21/streams_lookup_test.go
@@ -731,16 +731,16 @@ func TestEvmRegistry_MultiFeedRequest(t *testing.T) {
 			response: &MercuryV03Response{
 				Reports: []MercuryV03Report{
 					{
-						FeedID:                hexutil.MustDecode("0x4554482d5553442d415242495452554d2d544553544e45540000000000000000"),
+						FeedID:                "0x4554482d5553442d415242495452554d2d544553544e45540000000000000000",
 						ValidFromTimestamp:    123456,
 						ObservationsTimestamp: 123456,
-						FullReport:            hexutil.MustDecode("0xab2123dc00000012"),
+						FullReport:            "0xab2123dc00000012",
 					},
 					{
-						FeedID:                hexutil.MustDecode("0x4254432d5553442d415242495452554d2d544553544e45540000000000000000"),
+						FeedID:                "0x4254432d5553442d415242495452554d2d544553544e45540000000000000000",
 						ValidFromTimestamp:    123458,
 						ObservationsTimestamp: 123458,
-						FullReport:            hexutil.MustDecode("0xab2123dc00000016"),
+						FullReport:            "0xab2123dc00000016",
 					},
 				},
 			},
@@ -761,20 +761,49 @@ func TestEvmRegistry_MultiFeedRequest(t *testing.T) {
 			response: &MercuryV03Response{
 				Reports: []MercuryV03Report{
 					{
-						FeedID:                hexutil.MustDecode("0x4554482d5553442d415242495452554d2d544553544e45540000000000000000"),
+						FeedID:                "0x4554482d5553442d415242495452554d2d544553544e45540000000000000000",
 						ValidFromTimestamp:    123456,
 						ObservationsTimestamp: 123456,
-						FullReport:            hexutil.MustDecode("0xab2123dc00000012"),
+						FullReport:            "0xab2123dc00000012",
 					},
 					{
-						FeedID:                hexutil.MustDecode("0x4254432d5553442d415242495452554d2d544553544e45540000000000000000"),
+						FeedID:                "0x4254432d5553442d415242495452554d2d544553544e45540000000000000000",
 						ValidFromTimestamp:    123458,
 						ObservationsTimestamp: 123458,
-						FullReport:            hexutil.MustDecode("0xab2123dc00000019"),
+						FullReport:            "0xab2123dc00000019",
 					},
 				},
 			},
 		},
+		{
+			name: "failure - fail to decode reportBlob",
+			lookup: &StreamsLookup{
+				feedParamKey: feedIDs,
+				feeds:        []string{"0x4554482d5553442d415242495452554d2d544553544e45540000000000000000", "0x4254432d5553442d415242495452554d2d544553544e45540000000000000000"},
+				timeParamKey: timestamp,
+				time:         big.NewInt(123456),
+				upkeepId:     upkeepId,
+			},
+			response: &MercuryV03Response{
+				Reports: []MercuryV03Report{
+					{
+						FeedID:                "0x4554482d5553442d415242495452554d2d544553544e45540000000000000000",
+						ValidFromTimestamp:    123456,
+						ObservationsTimestamp: 123456,
+						FullReport:            "qerwiu", // invalid hex blob
+					},
+					{
+						FeedID:                "0x4254432d5553442d415242495452554d2d544553544e45540000000000000000",
+						ValidFromTimestamp:    123458,
+						ObservationsTimestamp: 123458,
+						FullReport:            "0xab2123dc00000016",
+					},
+				},
+			},
+			statusCode:   http.StatusOK,
+			retryable:    false,
+			errorMessage: "All attempts fail:\n#1: hex string without 0x prefix",
+		},
 		{
 			name: "failure - returns retryable",
 			lookup: &StreamsLookup{
@@ -839,26 +868,26 @@ func TestEvmRegistry_MultiFeedRequest(t *testing.T) {
 			firstResponse: &MercuryV03Response{
 				Reports: []MercuryV03Report{
 					{
-						FeedID:                hexutil.MustDecode("0x4554482d5553442d415242495452554d2d544553544e45540000000000000000"),
+						FeedID:                "0x4554482d5553442d415242495452554d2d544553544e45540000000000000000",
 						ValidFromTimestamp:    123456,
 						ObservationsTimestamp: 123456,
-						FullReport:            hexutil.MustDecode("0xab2123dc00000012"),
+						FullReport:            "0xab2123dc00000012",
 					},
 				},
 			},
 			response: &MercuryV03Response{
 				Reports: []MercuryV03Report{
 					{
-						FeedID:                hexutil.MustDecode("0x4554482d5553442d415242495452554d2d544553544e45540000000000000000"),
+						FeedID:                "0x4554482d5553442d415242495452554d2d544553544e45540000000000000000",
 						ValidFromTimestamp:    123456,
 						ObservationsTimestamp: 123456,
-						FullReport:            hexutil.MustDecode("0xab2123dc00000012"),
+						FullReport:            "0xab2123dc00000012",
 					},
 					{
-						FeedID:                hexutil.MustDecode("0x4254432d5553442d415242495452554d2d544553544e45540000000000000000"),
+						FeedID:                "0x4254432d5553442d415242495452554d2d544553544e45540000000000000000",
 						ValidFromTimestamp:    123458,
 						ObservationsTimestamp: 123458,
-						FullReport:            hexutil.MustDecode("0xab2123dc00000019"),
+						FullReport:            "0xab2123dc00000019",
 					},
 				},
 			},
@@ -930,7 +959,8 @@ func TestEvmRegistry_MultiFeedRequest(t *testing.T) {
 				assert.Nil(t, m.Error)
 				var reports [][]byte
 				for _, rsp := range tt.response.Reports {
-					reports = append(reports, rsp.FullReport)
+					b, _ := hexutil.Decode(rsp.FullReport)
+					reports = append(reports, b)
 				}
 				assert.Equal(t, reports, m.Bytes)
 			}