diff --git a/campaign/src/lib.rs b/campaign/src/lib.rs
index a83ffc7..b225021 100644
--- a/campaign/src/lib.rs
+++ b/campaign/src/lib.rs
@@ -790,6 +790,7 @@ pub fn validate_milestone_transition(
 #[cfg(test)]
 mod test {
     pub mod claim_refund_tests;
+    pub mod error_discriminant_tests;
     pub mod get_campaign_status_tests;
     pub mod integration_tests;
     pub mod invariant_tests;
diff --git a/campaign/src/test/error_discriminant_tests.rs b/campaign/src/test/error_discriminant_tests.rs
new file mode 100644
index 0000000..6c3f2a2
--- /dev/null
+++ b/campaign/src/test/error_discriminant_tests.rs
@@ -0,0 +1,72 @@
+use crate::types::Error;
+use common::ErrorCode;
+
+#[test]
+fn campaign_and_common_error_discriminants_do_not_collide() {
+    let campaign_codes = [
+        Error::AlreadyInitialized as u32,
+        Error::NotInitialized as u32,
+        Error::Unauthorized as u32,
+        Error::CampaignEnded as u32,
+        Error::CampaignNotActive as u32,
+        Error::AssetNotAccepted as u32,
+        Error::DonationTooSmall as u32,
+        Error::MilestoneNotFound as u32,
+        Error::MilestoneNotUnlocked as u32,
+        Error::PreviousMilestoneNotReleased as u32,
+        Error::CannotCancelWithFunds as u32,
+        Error::RefundWindowClosed as u32,
+        Error::InvalidGoalAmount as u32,
+        Error::InvalidEndTime as u32,
+        Error::InvalidMilestones as u32,
+        Error::InsufficientContractBalance as u32,
+        Error::Overflow as u32,
+        Error::InvalidAssets as u32,
+        Error::InvalidAssetCode as u32,
+        Error::MilestoneMismatch as u32,
+        Error::InvalidMilestoneCount as u32,
+        Error::InvalidCampaignTransition as u32,
+        Error::InvalidMilestoneTransition as u32,
+        Error::GoalNotReached as u32,
+        Error::InvalidStorageValue as u32,
+        Error::StorageWriteError as u32,
+        Error::InvalidRecipient as u32,
+        Error::MissingIssuerAddress as u32,
+        Error::ZeroReleaseAmount as u32,
+        Error::NothingToRelease as u32,
+        Error::MilestoneReleasedExceedsTarget as u32,
+        Error::MilestoneAlreadyReleased as u32,
+        Error::UnreleasedMilestonesExist as u32,
+        Error::RefundNotPermitted as u32,
+        Error::NoDonorRecord as u32,
+        Error::RefundAlreadyClaimed as u32,
+        Error::ReentrantCall as u32,
+        Error::InvalidAmount as u32,
+        Error::ContractFrozen as u32,
+    ];
+
+    let common_codes = [
+        ErrorCode::NotInitialized as u32,
+        ErrorCode::AlreadyInitialized as u32,
+        ErrorCode::Unauthorized as u32,
+        ErrorCode::InvalidAmount as u32,
+    ];
+
+    for common_code in common_codes {
+        assert!(
+            (1000..=1099).contains(&common_code),
+            "common error code {common_code} must stay in the shared 1000..=1099 namespace"
+        );
+        assert!(
+            !campaign_codes.contains(&common_code),
+            "common error code {common_code} collides with campaign::Error"
+        );
+    }
+
+    for campaign_code in campaign_codes {
+        assert!(
+            campaign_code < 1000,
+            "campaign error code {campaign_code} must stay below the shared common namespace"
+        );
+    }
+}
diff --git a/campaign/src/types.rs b/campaign/src/types.rs
index c70eac7..4788659 100644
--- a/campaign/src/types.rs
+++ b/campaign/src/types.rs
@@ -9,6 +9,10 @@ use soroban_sdk::{contracterror, contracttype, Address, BytesN, Env, String, Vec
 /// Codes are stable — never renumber an existing variant; only append new ones.
 /// Each code maps to a `u32` via `contracterror` and is surfaced in transaction
 /// results as `Error(Contract, #N)`.
+///
+/// Campaign owns the `1..=999` contract-local error namespace. Shared workspace
+/// errors from `common::ErrorCode` are reserved for `1000..=1099`; keep the two
+/// ranges disjoint whenever a new variant is added.
 #[contracterror]
 #[derive(Copy, Clone, Debug, Eq, PartialEq)]
 pub enum Error {
diff --git a/common/src/lib.rs b/common/src/lib.rs
index a41e8bf..938399f 100644
--- a/common/src/lib.rs
+++ b/common/src/lib.rs
@@ -1,10 +1,13 @@
 //! Common types shared across the OrbitChain workspace.
 //!
 //! This crate provides canonical definitions for `CampaignStatus`, `MilestoneStatus`,
-//! `AssetInfo`, and `ErrorCode` used by both campaign and core contracts.
+//! `AssetInfo`, and the shared error-code range used by both campaign and core
+//! contracts.
 //!
 //! # Versioning
-//! All discriminants are stable — never renumber existing variants.
+//! All discriminants are stable — never renumber existing variants. Shared
+//! workspace errors must stay in the `1000..=1099` range so they cannot collide
+//! with contract-local error enums such as `campaign::types::Error`.
 
 #![no_std]
 use soroban_sdk::{contracterror, contracttype};
@@ -44,11 +47,11 @@ pub struct AssetInfo {
 #[derive(Copy, Clone, Debug, Eq, PartialEq)]
 pub enum ErrorCode {
     /// Contract has not been initialized yet.
-    NotInitialized = 1,
+    NotInitialized = 1000,
     /// Contract has already been initialized.
-    AlreadyInitialized = 2,
+    AlreadyInitialized = 1001,
     /// Caller is not authorized to perform this operation.
-    Unauthorized = 3,
+    Unauthorized = 1002,
     /// The amount supplied is invalid (zero, negative, or out of range).
-    InvalidAmount = 4,
+    InvalidAmount = 1003,
 }
diff --git a/docs/deployment.md b/docs/deployment.md
index e0c9b8b..9b6ab66 100644
--- a/docs/deployment.md
+++ b/docs/deployment.md
@@ -47,6 +47,18 @@ timestamp. This prevents accidental or malicious `u64`-scale future dates from
 making status views, refund-window checks, milestone release arithmetic, and
 campaign reports meaningless while still allowing long-running campaigns.
 
+## Error-Code Migration Note
+
+`campaign::types::Error` owns the contract-local `1..=999` error namespace.
+`common::ErrorCode` owns the shared workspace `1000..=1099` namespace. This
+keeps `Error(Contract, #N)` values unambiguous for off-chain indexers and any
+future crate that imports both enums.
+
+If a deployed integration previously interpreted `common::ErrorCode` values as
+`1..=4`, migrate that integration before it consumes the shared crate again:
+`NotInitialized=1000`, `AlreadyInitialized=1001`, `Unauthorized=1002`, and
+`InvalidAmount=1003`. Campaign contract error values are unchanged.
+
 ## Troubleshooting
 
 - **`InsufficientFee`**: Add `--fee 1000000` to the deploy command.