diff --git a/contracts/Shared Wallet/SharedWallet.sol b/contracts/Shared Wallet/SharedWallet.sol
index bfd1940..6f96337 100644
--- a/contracts/Shared Wallet/SharedWallet.sol	
+++ b/contracts/Shared Wallet/SharedWallet.sol	
@@ -3,6 +3,7 @@
 pragma solidity ^0.8.9;
 
 contract SharedWallet {
+    error Insufficient__Balance( );
     address private _owner;
 
     mapping(address => bool) private _owners;
@@ -44,14 +45,18 @@ contract SharedWallet {
 
     // withdraw fund from the shared wallet into the signer of transaction
     function withdraw(uint256 amount) public validOwner {
-        require(address(this).balance >= amount);
+        if(address(this).balance<amount){
+            revert Insufficient__Balance(); 
+        }
         payable(msg.sender).transfer(amount);
         emit WithdrawFunds(msg.sender, amount);
     }
 
     // transfer fund from the shared wallet into another address
     function transferTo(address payable to, uint256 amount) public validOwner {
-        require(address(this).balance >= amount);
+        if(address(this).balance<amount){
+            revert Insufficient__Balance(); 
+        }
         payable(to).transfer(amount);
         emit TransferFunds(msg.sender, to, amount);
     }
diff --git a/contracts/TimeLock/TimeLock.sol b/contracts/TimeLock/TimeLock.sol
index 566b968..b68fc09 100644
--- a/contracts/TimeLock/TimeLock.sol
+++ b/contracts/TimeLock/TimeLock.sol
@@ -5,7 +5,8 @@ pragma solidity ^0.8.9;
 import '@openzeppelin/contracts/token/ERC20/IERC20.sol';
 
 contract TimeLock{
-    
+    error Only__Owner_Can_Withdraw();
+    error  Cannot_Withdraw_Before_EndTime(uint end_Time );
     uint public immutable endTime; //end time
     address payable public immutable owner; 
 
@@ -22,9 +23,12 @@ contract TimeLock{
     receive() external payable {}
 
     function withdraw(address token, uint amount) external {
-        require(msg.sender == owner, "Only owner can withdraw");
-        require(block.timestamp >= endTime, "Cannot withdraw before endTime");
-
+        if(msg.sender!=owner){
+            revert Only__Owner_Can_Withdraw(); 
+        }
+        if(block.timestamp<endTime){
+            revert Cannot_Withdraw_Before_EndTime(endTime);
+        }
         //number of tokens = 0, so we are just withdrawing ETH
         if(token == address(0)){
             owner.transfer(amount);
diff --git a/contracts/Voting/Election.sol b/contracts/Voting/Election.sol
index eaf15b5..14bf881 100644
--- a/contracts/Voting/Election.sol
+++ b/contracts/Voting/Election.sol
@@ -2,7 +2,9 @@
 pragma solidity ^0.8.4;
 
 contract Election {
-
+    error Voter__Already_Voted();
+    error Voter__Has__No_Right_To_Vote();
+    error Only__Chairperson_Can_Choose_Voters();
     // It will represent a single voter.
     struct Voter {
         uint weight; // weight is accumulated by delegation
@@ -46,14 +48,13 @@ contract Election {
     // Give `voter` the right to vote on this ballot.
     // May only be called by `chairperson`.
     function giveRightToVote(address voter) external {        
-        require(
-            msg.sender == chairperson,
-            "Only chairperson can give right to vote."
-        );
-        require(
-            !voters[voter].voted,
-            "The voter already voted."
-        );
+        if(msg.sender!=chairperson){
+            revert Only__Chairperson_Can_Choose_Voters();
+        }
+        if(voters[voter].voted){
+            revert Voter__Already_Voted() ;
+        }
+
         require(voters[voter].weight == 0);
         voters[voter].weight = 1;
     }
@@ -62,9 +63,12 @@ contract Election {
     function delegate(address to) external {
         // assigns reference
         Voter storage sender = voters[msg.sender];
-        require(sender.weight != 0, "You have no right to vote");
-        require(!sender.voted, "You already voted.");
-
+        if(sender.weight==0){
+            revert Voter__Has__No_Right_To_Vote();
+        }
+        if(sender.voted){
+            revert Voter__Already_Voted(); 
+        }
         require(to != msg.sender, "Self-delegation is disallowed.");
         while (voters[to].delegate != address(0)) {
             to = voters[to].delegate;
@@ -96,8 +100,12 @@ contract Election {
     /// to proposal `proposals[proposal].name`.
     function vote(uint proposal) external {
         Voter storage sender = voters[msg.sender];
-        require(sender.weight != 0, "Has no right to vote");
-        require(!sender.voted, "Already voted.");
+        if(sender.weight==0){
+            revert Voter__Has__No_Right_To_Vote();
+        }
+        if(sender.voted){
+            revert Voter__Already_Voted();
+        }
         sender.voted = true;
         sender.vote = proposal;