diff --git a/CHANGELOG.md b/CHANGELOG.md
index ff8f8bdf39..1f655666e4 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -19,6 +19,7 @@ We use *breaking :warning:* to mark changes that are not backward compatible (re
 - [#7122](https://github.com/thanos-io/thanos/pull/7122) Store Gateway: Fix lazy expanded postings estimate base cardinality using posting group with remove keys.
 - [#7224](https://github.com/thanos-io/thanos/pull/7224) Query-frontend: Add Redis username to the client configuration.
 - [#7220](https://github.com/thanos-io/thanos/pull/7220) Store Gateway: Fix lazy expanded postings caching partial expanded postings and bug of estimating remove postings with non existent value. Added `PromQLSmith` based fuzz test to improve correctness.
+- [#7244](https://github.com/thanos-io/thanos/pull/7244) Query: Fix Internal Server Error unknown targetHealth: "unknown" when trying to open the targets page.
 
 ### Added
 
diff --git a/pkg/targets/targetspb/rpc.pb.go b/pkg/targets/targetspb/rpc.pb.go
index da33a07575..5344c1905e 100644
--- a/pkg/targets/targetspb/rpc.pb.go
+++ b/pkg/targets/targetspb/rpc.pb.go
@@ -39,18 +39,21 @@ const _ = proto.GoGoProtoPackageIsVersion3 // please upgrade the proto package
 type TargetHealth int32
 
 const (
-	TargetHealth_DOWN TargetHealth = 0
-	TargetHealth_UP   TargetHealth = 1
+	TargetHealth_DOWN    TargetHealth = 0
+	TargetHealth_UP      TargetHealth = 1
+	TargetHealth_UNKNOWN TargetHealth = 2
 )
 
 var TargetHealth_name = map[int32]string{
 	0: "DOWN",
 	1: "UP",
+	2: "UNKNOWN",
 }
 
 var TargetHealth_value = map[string]int32{
-	"DOWN": 0,
-	"UP":   1,
+	"DOWN":    0,
+	"UP":      1,
+	"UNKNOWN": 2,
 }
 
 func (x TargetHealth) String() string {
@@ -347,51 +350,51 @@ func init() {
 func init() { proto.RegisterFile("targets/targetspb/rpc.proto", fileDescriptor_b5cdaee03579e907) }
 
 var fileDescriptor_b5cdaee03579e907 = []byte{
-	// 694 bytes of a gzipped FileDescriptorProto
-	0x1f, 0x8b, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x02, 0xff, 0xb4, 0x54, 0x41, 0x4f, 0xdb, 0x4a,
-	0x10, 0xb6, 0x03, 0x38, 0x64, 0x80, 0xbc, 0xb0, 0xe2, 0x81, 0xc9, 0x7b, 0x8a, 0x51, 0x2e, 0x8f,
-	0xd7, 0x4a, 0x4e, 0x15, 0x2e, 0xad, 0xd4, 0x0b, 0x6e, 0x68, 0xa9, 0xd4, 0x42, 0xba, 0x09, 0x45,
-	0xa5, 0x07, 0xb4, 0x49, 0xb6, 0x4e, 0x24, 0x93, 0x75, 0x77, 0x37, 0x54, 0xfc, 0x0b, 0xfe, 0x49,
-	0x0f, 0xfd, 0x13, 0x1c, 0x7a, 0xe0, 0xd8, 0x93, 0xdb, 0xc2, 0x2d, 0xbf, 0xa2, 0xf2, 0xda, 0x8e,
-	0x1d, 0x48, 0x8f, 0xbd, 0x78, 0x67, 0xbe, 0xf9, 0xe6, 0x9b, 0x59, 0xef, 0xce, 0xc2, 0x3f, 0x92,
-	0x70, 0x97, 0x4a, 0x51, 0x8b, 0x57, 0xbf, 0x53, 0xe3, 0x7e, 0xd7, 0xf6, 0x39, 0x93, 0x0c, 0x19,
-	0xb2, 0x4f, 0x86, 0x4c, 0x94, 0x37, 0x85, 0x64, 0x9c, 0xd6, 0xd4, 0xd7, 0xef, 0xd4, 0xe4, 0x85,
-	0x4f, 0x45, 0x44, 0x29, 0xaf, 0xb9, 0xcc, 0x65, 0xca, 0xac, 0x85, 0x56, 0x8c, 0xc6, 0x09, 0x1e,
-	0xe9, 0x50, 0xef, 0x4e, 0x82, 0xe5, 0x32, 0xe6, 0x7a, 0xb4, 0xa6, 0xbc, 0xce, 0xe8, 0x43, 0x4d,
-	0x0e, 0xce, 0xa8, 0x90, 0xe4, 0xcc, 0x8f, 0x08, 0xd5, 0xaf, 0x3a, 0x14, 0xdb, 0x51, 0x33, 0x98,
-	0x7e, 0x1c, 0x51, 0x21, 0x51, 0x1d, 0x16, 0x84, 0x24, 0x92, 0x9a, 0xfa, 0x96, 0xbe, 0x5d, 0xac,
-	0xff, 0x6b, 0x47, 0x7d, 0xd9, 0xd3, 0x34, 0xbb, 0x15, 0x72, 0x70, 0x44, 0x45, 0xef, 0x61, 0xd3,
-	0x27, 0x5c, 0x0e, 0x88, 0x77, 0xca, 0xa9, 0xf0, 0xd9, 0x50, 0xd0, 0x53, 0x21, 0x39, 0x91, 0xd4,
-	0xbd, 0x30, 0x73, 0x4a, 0xc7, 0x4a, 0x74, 0x9a, 0x11, 0x11, 0xc7, 0xbc, 0x56, 0x4c, 0xc3, 0x1b,
-	0xfe, 0xec, 0x40, 0xf5, 0x7f, 0x58, 0x50, 0xc5, 0x50, 0x1e, 0xe6, 0x76, 0x0f, 0xde, 0x95, 0x34,
-	0x04, 0x60, 0xec, 0x3e, 0x6b, 0xbf, 0x7c, 0xbb, 0x57, 0xd2, 0xd1, 0x12, 0xe4, 0x1b, 0xf8, 0xb0,
-	0xd9, 0xdc, 0x6b, 0x94, 0x72, 0x55, 0x0f, 0xfe, 0x9a, 0xb4, 0x19, 0xa9, 0xa0, 0x1d, 0xc8, 0xc7,
-	0x7f, 0x5b, 0x6d, 0x68, 0xa9, 0xbe, 0x31, 0xbd, 0xa1, 0xc6, 0x40, 0x74, 0xd9, 0x39, 0xe5, 0x17,
-	0xfb, 0x1a, 0x4e, 0x98, 0xa8, 0x0c, 0xf9, 0x4f, 0x84, 0x0f, 0x07, 0x43, 0x57, 0x75, 0x5f, 0x08,
-	0x63, 0x31, 0xe0, 0x2c, 0x82, 0xc1, 0xa9, 0x18, 0x79, 0xb2, 0xfa, 0x45, 0x4f, 0xca, 0x4d, 0x44,
-	0xd0, 0x6b, 0x58, 0x21, 0x5d, 0x39, 0x38, 0xa7, 0xed, 0x49, 0xd1, 0xb9, 0xed, 0xa5, 0xfa, 0x5a,
-	0x52, 0x74, 0x37, 0x13, 0x74, 0x56, 0xc7, 0x81, 0x35, 0x4d, 0xc7, 0xd3, 0x2e, 0x7a, 0x03, 0xc5,
-	0x1e, 0x67, 0xbe, 0x4f, 0x7b, 0x89, 0x5e, 0x4e, 0xe9, 0xfd, 0x9d, 0xe8, 0x35, 0xb2, 0x51, 0x07,
-	0x8d, 0x03, 0xeb, 0x4e, 0x02, 0xbe, 0xe3, 0x57, 0x3f, 0xcf, 0xc3, 0x72, 0xb6, 0x0b, 0x74, 0x0c,
-	0xa5, 0x5e, 0xdc, 0x3f, 0xed, 0xbd, 0x0a, 0x6f, 0x51, 0xf2, 0xab, 0x56, 0x93, 0x2a, 0x27, 0x0a,
-	0x6e, 0x51, 0xe9, 0x98, 0x57, 0x81, 0xa5, 0x8d, 0x03, 0xeb, 0x5e, 0x0a, 0xbe, 0x87, 0xa0, 0x27,
-	0x60, 0x78, 0x91, 0x5c, 0xee, 0x77, 0x72, 0xc5, 0x58, 0x2e, 0x26, 0xe2, 0x78, 0x45, 0x36, 0x80,
-	0xe8, 0x72, 0xe2, 0xd3, 0x26, 0x63, 0x9e, 0x39, 0x17, 0x9e, 0x81, 0x53, 0x1c, 0x07, 0x56, 0x06,
-	0xc5, 0x19, 0x1b, 0x3d, 0x84, 0x42, 0xe4, 0x1d, 0x71, 0xcf, 0x9c, 0x57, 0xf4, 0x95, 0x71, 0x60,
-	0xa5, 0x20, 0x4e, 0xcd, 0x90, 0xec, 0x7a, 0xac, 0x43, 0xbc, 0x90, 0xbc, 0x90, 0x92, 0x27, 0x20,
-	0x4e, 0xcd, 0x90, 0xec, 0x11, 0x21, 0xf7, 0x38, 0x67, 0xdc, 0x34, 0x52, 0xf2, 0x04, 0xc4, 0xa9,
-	0x89, 0x30, 0x40, 0xe8, 0xb4, 0x54, 0x29, 0x33, 0xaf, 0x76, 0x5d, 0xb6, 0xa3, 0x21, 0xb4, 0x93,
-	0x21, 0xb4, 0xdb, 0xc9, 0x10, 0x3a, 0xeb, 0xf1, 0xf6, 0x33, 0x59, 0x97, 0xdf, 0x2d, 0x1d, 0x67,
-	0x7c, 0xf4, 0x1c, 0x50, 0xea, 0x35, 0x46, 0x9c, 0xc8, 0x01, 0x1b, 0x9a, 0x8b, 0x5b, 0xfa, 0xb6,
-	0xee, 0xac, 0x8f, 0x03, 0x6b, 0x46, 0x14, 0xcf, 0xc0, 0xd0, 0x63, 0x30, 0xfa, 0x94, 0x78, 0xb2,
-	0x6f, 0x16, 0xd4, 0x40, 0xae, 0x4d, 0xcf, 0xc1, 0xbe, 0x8a, 0x39, 0x10, 0x1e, 0x46, 0xc4, 0xc3,
-	0xf1, 0x5a, 0xed, 0xc3, 0xca, 0xd4, 0x35, 0xfb, 0x63, 0x37, 0xe6, 0xc1, 0x16, 0x2c, 0x67, 0xbb,
-	0x41, 0x8b, 0x30, 0xdf, 0x38, 0x3c, 0x3e, 0x28, 0x69, 0xc8, 0x80, 0xdc, 0x51, 0xb3, 0xa4, 0xd7,
-	0x5f, 0x40, 0x3e, 0x99, 0x8d, 0xa7, 0xa9, 0xb9, 0x3e, 0xfb, 0x91, 0x2a, 0x6f, 0xdc, 0xc3, 0xa3,
-	0x57, 0xe1, 0x91, 0xee, 0xfc, 0x77, 0xf5, 0xb3, 0xa2, 0x5d, 0xdd, 0x54, 0xf4, 0xeb, 0x9b, 0x8a,
-	0xfe, 0xe3, 0xa6, 0xa2, 0x5f, 0xde, 0x56, 0xb4, 0xeb, 0xdb, 0x8a, 0xf6, 0xed, 0xb6, 0xa2, 0x9d,
-	0x14, 0x26, 0x2f, 0x74, 0xc7, 0x50, 0xe7, 0xb6, 0xf3, 0x2b, 0x00, 0x00, 0xff, 0xff, 0xf2, 0x61,
-	0x2b, 0xab, 0xbd, 0x05, 0x00, 0x00,
+	// 702 bytes of a gzipped FileDescriptorProto
+	0x1f, 0x8b, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x02, 0xff, 0xb4, 0x54, 0x41, 0x53, 0xdb, 0x3a,
+	0x10, 0xb6, 0x03, 0x38, 0x64, 0x81, 0xbc, 0xa0, 0xe1, 0x81, 0xc9, 0x7b, 0x13, 0x33, 0xb9, 0x3c,
+	0x5e, 0x3b, 0x75, 0x3a, 0xe1, 0xd2, 0xce, 0xf4, 0x82, 0x1b, 0x5a, 0x3a, 0x6d, 0x43, 0xaa, 0x84,
+	0x32, 0xa5, 0x07, 0x46, 0x49, 0x54, 0x27, 0x33, 0x26, 0x72, 0x25, 0x85, 0x0e, 0xff, 0x82, 0x7f,
+	0xd2, 0x43, 0xff, 0x04, 0x87, 0x1e, 0x38, 0xf6, 0x94, 0xb6, 0x70, 0xcb, 0xaf, 0xe8, 0x58, 0xb6,
+	0x63, 0x07, 0xd2, 0x63, 0x2f, 0xd6, 0xee, 0xb7, 0xdf, 0x7e, 0xbb, 0xb2, 0xb4, 0x82, 0x7f, 0x24,
+	0xe1, 0x2e, 0x95, 0xa2, 0x12, 0xad, 0x7e, 0xbb, 0xc2, 0xfd, 0x8e, 0xed, 0x73, 0x26, 0x19, 0x32,
+	0x64, 0x8f, 0x0c, 0x98, 0x28, 0x6e, 0x0a, 0xc9, 0x38, 0xad, 0xa8, 0xaf, 0xdf, 0xae, 0xc8, 0x73,
+	0x9f, 0x8a, 0x90, 0x52, 0x5c, 0x73, 0x99, 0xcb, 0x94, 0x59, 0x09, 0xac, 0x08, 0x8d, 0x12, 0x3c,
+	0xd2, 0xa6, 0xde, 0xad, 0x04, 0xcb, 0x65, 0xcc, 0xf5, 0x68, 0x45, 0x79, 0xed, 0xe1, 0x87, 0x8a,
+	0xec, 0x9f, 0x52, 0x21, 0xc9, 0xa9, 0x1f, 0x12, 0xca, 0x5f, 0x75, 0xc8, 0xb7, 0xc2, 0x66, 0x30,
+	0xfd, 0x38, 0xa4, 0x42, 0xa2, 0x2a, 0x2c, 0x08, 0x49, 0x24, 0x35, 0xf5, 0x2d, 0x7d, 0x3b, 0x5f,
+	0xfd, 0xd7, 0x0e, 0xfb, 0xb2, 0xa7, 0x69, 0x76, 0x33, 0xe0, 0xe0, 0x90, 0x8a, 0xde, 0xc3, 0xa6,
+	0x4f, 0xb8, 0xec, 0x13, 0xef, 0x84, 0x53, 0xe1, 0xb3, 0x81, 0xa0, 0x27, 0x42, 0x72, 0x22, 0xa9,
+	0x7b, 0x6e, 0x66, 0x94, 0x8e, 0x15, 0xeb, 0x34, 0x42, 0x22, 0x8e, 0x78, 0xcd, 0x88, 0x86, 0x37,
+	0xfc, 0xd9, 0x81, 0xf2, 0xff, 0xb0, 0xa0, 0x8a, 0xa1, 0x2c, 0xcc, 0xed, 0xd6, 0xdf, 0x15, 0x34,
+	0x04, 0x60, 0xec, 0x3e, 0x6d, 0xbd, 0x78, 0xbb, 0x57, 0xd0, 0xd1, 0x12, 0x64, 0x6b, 0xf8, 0xa0,
+	0xd1, 0xd8, 0xab, 0x15, 0x32, 0x65, 0x0f, 0xfe, 0x9a, 0xb4, 0x19, 0xaa, 0xa0, 0x1d, 0xc8, 0x46,
+	0x7f, 0x5b, 0x6d, 0x68, 0xa9, 0xba, 0x31, 0xbd, 0xa1, 0x5a, 0x5f, 0x74, 0xd8, 0x19, 0xe5, 0xe7,
+	0xfb, 0x1a, 0x8e, 0x99, 0xa8, 0x08, 0xd9, 0x4f, 0x84, 0x0f, 0xfa, 0x03, 0x57, 0x75, 0x9f, 0x0b,
+	0x62, 0x11, 0xe0, 0x2c, 0x82, 0xc1, 0xa9, 0x18, 0x7a, 0xb2, 0xfc, 0x45, 0x8f, 0xcb, 0x4d, 0x44,
+	0xd0, 0x6b, 0x58, 0x21, 0x1d, 0xd9, 0x3f, 0xa3, 0xad, 0x49, 0xd1, 0xb9, 0xed, 0xa5, 0xea, 0x5a,
+	0x5c, 0x74, 0x37, 0x15, 0x74, 0x56, 0xc7, 0x23, 0x6b, 0x9a, 0x8e, 0xa7, 0x5d, 0xf4, 0x06, 0xf2,
+	0x5d, 0xce, 0x7c, 0x9f, 0x76, 0x63, 0xbd, 0x8c, 0xd2, 0xfb, 0x3b, 0xd6, 0xab, 0xa5, 0xa3, 0x0e,
+	0x1a, 0x8f, 0xac, 0x5b, 0x09, 0xf8, 0x96, 0x5f, 0xfe, 0x3c, 0x0f, 0xcb, 0xe9, 0x2e, 0xd0, 0x11,
+	0x14, 0xba, 0x51, 0xff, 0xb4, 0xfb, 0x2a, 0xb8, 0x45, 0xf1, 0xaf, 0x5a, 0x8d, 0xab, 0x1c, 0x2b,
+	0xb8, 0x49, 0xa5, 0x63, 0x5e, 0x8e, 0x2c, 0x6d, 0x3c, 0xb2, 0xee, 0xa4, 0xe0, 0x3b, 0x08, 0x7a,
+	0x0c, 0x86, 0x17, 0xca, 0x65, 0x7e, 0x27, 0x97, 0x8f, 0xe4, 0x22, 0x22, 0x8e, 0x56, 0x64, 0x03,
+	0x88, 0x0e, 0x27, 0x3e, 0x6d, 0x30, 0xe6, 0x99, 0x73, 0xc1, 0x19, 0x38, 0xf9, 0xf1, 0xc8, 0x4a,
+	0xa1, 0x38, 0x65, 0xa3, 0xfb, 0x90, 0x0b, 0xbd, 0x43, 0xee, 0x99, 0xf3, 0x8a, 0xbe, 0x32, 0x1e,
+	0x59, 0x09, 0x88, 0x13, 0x33, 0x20, 0xbb, 0x1e, 0x6b, 0x13, 0x2f, 0x20, 0x2f, 0x24, 0xe4, 0x09,
+	0x88, 0x13, 0x33, 0x20, 0x7b, 0x44, 0xc8, 0x3d, 0xce, 0x19, 0x37, 0x8d, 0x84, 0x3c, 0x01, 0x71,
+	0x62, 0x22, 0x0c, 0x10, 0x38, 0x4d, 0x55, 0xca, 0xcc, 0xaa, 0x5d, 0x17, 0xed, 0x70, 0x08, 0xed,
+	0x78, 0x08, 0xed, 0x56, 0x3c, 0x84, 0xce, 0x7a, 0xb4, 0xfd, 0x54, 0xd6, 0xc5, 0x77, 0x4b, 0xc7,
+	0x29, 0x1f, 0x3d, 0x03, 0x94, 0x78, 0xb5, 0x21, 0x27, 0xb2, 0xcf, 0x06, 0xe6, 0xe2, 0x96, 0xbe,
+	0xad, 0x3b, 0xeb, 0xe3, 0x91, 0x35, 0x23, 0x8a, 0x67, 0x60, 0xe8, 0x11, 0x18, 0x3d, 0x4a, 0x3c,
+	0xd9, 0x33, 0x73, 0x6a, 0x20, 0xd7, 0xa6, 0xe7, 0x60, 0x5f, 0xc5, 0x1c, 0x08, 0x0e, 0x23, 0xe4,
+	0xe1, 0x68, 0x2d, 0xf7, 0x60, 0x65, 0xea, 0x9a, 0xfd, 0xb1, 0x1b, 0x73, 0xef, 0x01, 0x2c, 0xa7,
+	0xbb, 0x41, 0x8b, 0x30, 0x5f, 0x3b, 0x38, 0xaa, 0x17, 0x34, 0x64, 0x40, 0xe6, 0xb0, 0x11, 0x8e,
+	0xfb, 0x61, 0xfd, 0x65, 0x3d, 0x00, 0x33, 0xd5, 0xe7, 0x90, 0x8d, 0x07, 0xe5, 0x49, 0x62, 0xae,
+	0xcf, 0x7e, 0xb1, 0x8a, 0x1b, 0x77, 0xf0, 0xf0, 0x89, 0x78, 0xa8, 0x3b, 0xff, 0x5d, 0xfe, 0x2c,
+	0x69, 0x97, 0xd7, 0x25, 0xfd, 0xea, 0xba, 0xa4, 0xff, 0xb8, 0x2e, 0xe9, 0x17, 0x37, 0x25, 0xed,
+	0xea, 0xa6, 0xa4, 0x7d, 0xbb, 0x29, 0x69, 0xc7, 0xb9, 0xc9, 0x73, 0xdd, 0x36, 0xd4, 0x21, 0xee,
+	0xfc, 0x0a, 0x00, 0x00, 0xff, 0xff, 0x2a, 0x5c, 0x84, 0x60, 0xca, 0x05, 0x00, 0x00,
 }
 
 // Reference imports to suppress errors if they are not otherwise used.
diff --git a/pkg/targets/targetspb/rpc.proto b/pkg/targets/targetspb/rpc.proto
index 61863f61b8..6515dc0070 100644
--- a/pkg/targets/targetspb/rpc.proto
+++ b/pkg/targets/targetspb/rpc.proto
@@ -60,6 +60,7 @@ message TargetDiscovery {
 enum TargetHealth {
     DOWN = 0;
     UP = 1;
+    UNKNOWN = 2;
 }
 
 message ActiveTarget {