diff --git a/rust/chains/tw_polkadot/src/call_encoder/generic.rs b/rust/chains/tw_polkadot/src/call_encoder/generic.rs
index b33e224af4c..6df67ee4c53 100644
--- a/rust/chains/tw_polkadot/src/call_encoder/generic.rs
+++ b/rust/chains/tw_polkadot/src/call_encoder/generic.rs
@@ -77,7 +77,7 @@ impl GenericBalances {
         match &b.message_oneof {
             BalanceVariant::transfer(t) => Self::encode_transfer(ctx, t),
             BalanceVariant::asset_transfer(t) => Self::encode_asset_transfer(ctx, t),
-            _ => Err(EncodeError::InvalidCallIndex),
+            _ => Err(EncodeError::NotSupported),
         }
     }
 }
@@ -229,7 +229,7 @@ impl GenericStaking {
             StakingVariant::withdraw_unbonded(b) => Self::encode_withdraw_unbonded(b),
             StakingVariant::rebond(b) => Self::encode_rebond(b),
             StakingVariant::nominate(b) => Self::encode_nominate(ctx, b),
-            _ => Err(EncodeError::InvalidCallIndex),
+            _ => Err(EncodeError::NotSupported),
         }
     }
 }
diff --git a/rust/chains/tw_polkadot/src/call_encoder/polkadot.rs b/rust/chains/tw_polkadot/src/call_encoder/polkadot.rs
index 1f95ba21274..fe48ce7802f 100644
--- a/rust/chains/tw_polkadot/src/call_encoder/polkadot.rs
+++ b/rust/chains/tw_polkadot/src/call_encoder/polkadot.rs
@@ -31,7 +31,7 @@ impl TWPolkadotCallEncoder for PolkadotCallEncoder {
                 GenericStaking::encode_call(&self.0, s)?.map(PolkadotCall::Staking)
             },
             _ => {
-                return Err(EncodeError::InvalidCallIndex);
+                return Err(EncodeError::NotSupported);
             },
         };
         Ok(RawOwned(call.to_scale()))
@@ -70,7 +70,7 @@ impl TWPolkadotCallEncoder for KusamaCallEncoder {
                 GenericStaking::encode_call(&self.0, s)?.map(KusamaCall::Staking)
             },
             _ => {
-                return Err(EncodeError::InvalidCallIndex);
+                return Err(EncodeError::NotSupported);
             },
         };
         Ok(RawOwned(call.to_scale()))
diff --git a/rust/chains/tw_polkadot/src/call_encoder/polymesh.rs b/rust/chains/tw_polkadot/src/call_encoder/polymesh.rs
index 0d91ed300b1..72371776150 100644
--- a/rust/chains/tw_polkadot/src/call_encoder/polymesh.rs
+++ b/rust/chains/tw_polkadot/src/call_encoder/polymesh.rs
@@ -81,7 +81,7 @@ impl PolymeshBalances {
     pub fn encode_call(b: &Balance) -> WithCallIndexResult<Self> {
         match &b.message_oneof {
             BalanceVariant::transfer(t) => Self::encode_transfer(t),
-            _ => Err(EncodeError::InvalidCallIndex),
+            _ => Err(EncodeError::NotSupported),
         }
     }
 }
@@ -175,7 +175,7 @@ impl PolymeshIdentity {
         match &ident.message_oneof {
             IdentityVariant::join_identity_as_key(t) => Self::encode_join_identity(t),
             IdentityVariant::add_authorization(a) => Self::encode_add_authorization(a),
-            _ => Err(EncodeError::InvalidCallIndex),
+            _ => Err(EncodeError::NotSupported),
         }
     }
 }
@@ -295,7 +295,7 @@ impl PolymeshStaking {
             StakingVariant::withdraw_unbonded(b) => Self::encode_withdraw_unbonded(b),
             StakingVariant::rebond(b) => Self::encode_rebond(b),
             StakingVariant::nominate(b) => Self::encode_nominate(b),
-            _ => Err(EncodeError::InvalidCallIndex),
+            _ => Err(EncodeError::NotSupported),
         }
     }
 }
@@ -329,14 +329,14 @@ impl TWPolkadotCallEncoder for PolymeshCallEncoder {
                     PolymeshIdentity::encode_call(msg)?.map(PolymeshCall::Identity)
                 },
                 PolymeshVariant::None => {
-                    return Err(EncodeError::InvalidCallIndex);
+                    return Err(EncodeError::NotSupported);
                 },
             },
             SigningVariant::staking_call(s) => {
                 PolymeshStaking::encode_call(s)?.map(PolymeshCall::Staking)
             },
             SigningVariant::None => {
-                return Err(EncodeError::InvalidCallIndex);
+                return Err(EncodeError::NotSupported);
             },
         };
         Ok(RawOwned(call.to_scale()))
diff --git a/rust/frameworks/tw_substrate/src/extrinsic.rs b/rust/frameworks/tw_substrate/src/extrinsic.rs
index cf9026703e0..665bfa55eb7 100644
--- a/rust/frameworks/tw_substrate/src/extrinsic.rs
+++ b/rust/frameworks/tw_substrate/src/extrinsic.rs
@@ -48,7 +48,7 @@ impl CallIndex {
 
     pub fn required_from_tw(call_index: Option<(i32, i32)>) -> Result<Self, EncodeError> {
         if call_index.is_none() {
-            return Err(EncodeError::MissingCallIndicesTable);
+            return Err(EncodeError::MissingCallIndices);
         }
         Self::from_tw(call_index)
     }
diff --git a/rust/frameworks/tw_substrate/src/lib.rs b/rust/frameworks/tw_substrate/src/lib.rs
index c8f227f9fe9..a4298a44562 100644
--- a/rust/frameworks/tw_substrate/src/lib.rs
+++ b/rust/frameworks/tw_substrate/src/lib.rs
@@ -19,10 +19,11 @@ pub use extensions::*;
 #[derive(Debug, Clone, Eq, PartialEq)]
 pub enum EncodeError {
     InvalidNetworkId,
-    MissingCallIndicesTable,
+    MissingCallIndices,
     InvalidCallIndex,
     InvalidAddress,
     InvalidValue,
+    NotSupported,
 }
 
 impl From<EncodeError> for SigningError {
@@ -31,7 +32,8 @@ impl From<EncodeError> for SigningError {
         TWError::new(match err {
             EncodeError::InvalidAddress => SigningErrorType::Error_invalid_address,
             EncodeError::InvalidValue => SigningErrorType::Error_input_parse,
-            EncodeError::MissingCallIndicesTable => SigningErrorType::Error_not_supported,
+            EncodeError::MissingCallIndices => SigningErrorType::Error_not_supported,
+            EncodeError::NotSupported => SigningErrorType::Error_not_supported,
             _ => SigningErrorType::Error_invalid_params,
         })
         .context(format!("{err:?}"))