diff --git a/library/src/main/java/ch/decent/sdk/model/FeeSchedule.kt b/library/src/main/java/ch/decent/sdk/model/FeeSchedule.kt
index c33e4b1c..54615f65 100644
--- a/library/src/main/java/ch/decent/sdk/model/FeeSchedule.kt
+++ b/library/src/main/java/ch/decent/sdk/model/FeeSchedule.kt
@@ -3,6 +3,9 @@ package ch.decent.sdk.model
 import com.google.gson.annotations.SerializedName
 
 data class FeeSchedule(
-    @SerializedName("parameters") val parameters: Map<OperationType, FeeParameter>,
+    /**
+     * operation types int keys
+     */
+    @SerializedName("parameters") val parameters: Map<Int, FeeParameter>,
     @SerializedName("scale") val scale: Long
-)
\ No newline at end of file
+)
diff --git a/library/src/main/java/ch/decent/sdk/model/ObjectType.kt b/library/src/main/java/ch/decent/sdk/model/ObjectType.kt
index 7cd7fda4..14c18c8c 100644
--- a/library/src/main/java/ch/decent/sdk/model/ObjectType.kt
+++ b/library/src/main/java/ch/decent/sdk/model/ObjectType.kt
@@ -38,13 +38,14 @@ enum class ObjectType {
   SUBSCRIPTION_OBJECT, //15
   SEEDING_STATISTICS_OBJECT,
   TRANSACTION_DETAIL_OBJECT,
-  MESSAGING_OBJECT;
+  MESSAGING_OBJECT,
+  UNKNOWN_OBJECT;
 
   val space: Byte
-    get() = if (ordinal < 10) 1 else 2
+    get() = if (ordinal < GLOBAL_PROPERTY_OBJECT.ordinal) 1 else 2
 
   val type: Byte
-    get() = (ordinal - (space - 1) * 10).toByte()
+    get() = (ordinal - (space - 1) * GLOBAL_PROPERTY_OBJECT.ordinal).toByte()
 
   /**
    * This method is used to return the generic object type in the form space.type.0.
@@ -58,6 +59,6 @@ enum class ObjectType {
     get() = ChainObject(this)
 
   companion object {
-    fun fromSpaceType(space: Int, type: Int) = ObjectType.values()[max(space - 1, 0) * 10 + type]
+    fun fromSpaceType(space: Int, type: Int) = values().getOrElse(max(space - 1, 0) * GLOBAL_PROPERTY_OBJECT.ordinal + type) { UNKNOWN_OBJECT }
   }
 }
diff --git a/library/src/main/java/ch/decent/sdk/model/OperationType.kt b/library/src/main/java/ch/decent/sdk/model/OperationType.kt
index 189fc67e..0e433d86 100644
--- a/library/src/main/java/ch/decent/sdk/model/OperationType.kt
+++ b/library/src/main/java/ch/decent/sdk/model/OperationType.kt
@@ -45,10 +45,5 @@ enum class OperationType(val clazz: Class<*>? = null) {
   READY_TO_PUBLISH2_OPERATION,
   TRANSFER2_OPERATION(TransferOperation::class.java),
   UPDATE_USER_ISSUED_ASSET_ADVANCED,
-  DISALLOW_AUTOMATIC_RENEWAL_OF_SUBSCRIPTION_OPERATION,  // VIRTUAL 41
-  RETURN_ESCROW_SUBMISSION_OPERATION,                    // VIRTUAL
-  RETURN_ESCROW_BUYING_OPERATION,                        // VIRTUAL
-  PAY_SEEDER_OPERATION,                                  // VIRTUAL
-  FINISH_BUYING_OPERATION,                               // VIRTUAL 45
-  RENEWAL_OF_SUBSCRIPTION_OPERATION                      // VIRTUAL
-}
\ No newline at end of file
+  UNKNOWN_OPERATION
+}
diff --git a/library/src/main/java/ch/decent/sdk/model/Operations.kt b/library/src/main/java/ch/decent/sdk/model/Operations.kt
index 0df858c4..8eca1ab7 100644
--- a/library/src/main/java/ch/decent/sdk/model/Operations.kt
+++ b/library/src/main/java/ch/decent/sdk/model/Operations.kt
@@ -2,7 +2,11 @@ package ch.decent.sdk.model
 
 import ch.decent.sdk.crypto.Address
 import ch.decent.sdk.crypto.Credentials
-import ch.decent.sdk.net.serialization.*
+import ch.decent.sdk.net.serialization.ByteSerializable
+import ch.decent.sdk.net.serialization.Varint
+import ch.decent.sdk.net.serialization.VoteId
+import ch.decent.sdk.net.serialization.bytes
+import ch.decent.sdk.net.serialization.optionalBytes
 import ch.decent.sdk.utils.hex
 import ch.decent.sdk.utils.publicElGamal
 import ch.decent.sdk.utils.unhex
@@ -38,6 +42,15 @@ sealed class BaseOperation(
   override fun hashCode(): Int = Arrays.hashCode(bytes)
 }
 
+class UnknownOperation(val id: Int) : BaseOperation(OperationType.UNKNOWN_OPERATION) {
+  override val bytes: ByteArray
+    get() = byteArrayOf()
+
+  override fun toString(): String {
+    return "UnknownOperation(id=$id)"
+  }
+}
+
 class EmptyOperation(type: OperationType) : BaseOperation(type) {
   override val bytes: ByteArray
     get() = byteArrayOf(0)
@@ -351,4 +364,4 @@ class SendMessageOperation constructor(
     messagePayloadJson: String,
     payer: ChainObject,
     requiredAuths: List<ChainObject> = listOf(payer)
-) : CustomOperation(CustomOperationType.MESSAGING, payer, requiredAuths, messagePayloadJson.toByteArray().hex())
\ No newline at end of file
+) : CustomOperation(CustomOperationType.MESSAGING, payer, requiredAuths, messagePayloadJson.toByteArray().hex())
diff --git a/library/src/main/java/ch/decent/sdk/model/TypeAdapters.kt b/library/src/main/java/ch/decent/sdk/model/TypeAdapters.kt
index 2a4c0fdd..f84bbcf1 100644
--- a/library/src/main/java/ch/decent/sdk/model/TypeAdapters.kt
+++ b/library/src/main/java/ch/decent/sdk/model/TypeAdapters.kt
@@ -71,9 +71,11 @@ object OperationTypeFactory : TypeAdapterFactory {
 
         override fun read(reader: JsonReader): T? {
           val el = Streams.parse(reader)
-          val op = OperationType.values()[el.asJsonArray[0].asInt]
+          val idx = el.asJsonArray[0].asInt
+          val op = OperationType.values().getOrElse(idx) { OperationType.UNKNOWN_OPERATION }
           val obj = el.asJsonArray[1].asJsonObject
-          return op.clazz?.let {
+          return if (op == OperationType.UNKNOWN_OPERATION) UnknownOperation(idx) as T?
+          else op.clazz?.let {
             val delegate = gson.getDelegateAdapter(this@OperationTypeFactory, TypeToken.get(it))
             (delegate.fromJsonTree(obj) as BaseOperation).apply { this.type = op } as T?
           } ?: EmptyOperation(op) as T?
@@ -178,5 +180,5 @@ object OperationTypeAdapter : TypeAdapter<OperationType>() {
     out.value(value.ordinal)
   }
 
-  override fun read(reader: JsonReader): OperationType = OperationType.values()[reader.nextInt()]
-}
\ No newline at end of file
+  override fun read(reader: JsonReader): OperationType = OperationType.values().getOrElse(reader.nextInt()) { OperationType.UNKNOWN_OPERATION }
+}