diff --git a/Sources/Web3Core/Contract/ContractProtocol.swift b/Sources/Web3Core/Contract/ContractProtocol.swift
index c532a1934..5a2ab8863 100755
--- a/Sources/Web3Core/Contract/ContractProtocol.swift
+++ b/Sources/Web3Core/Contract/ContractProtocol.swift
@@ -356,7 +356,7 @@ extension DefaultContractProtocol {
                 throw Web3Error.inputError(desc: "Make sure ABI you use contains error that can match signature: 0x\(selector.toHexString())")
             }
         default:
-            throw Web3Error.inputError(desc: "Invalid data count")
+            throw Web3Error.inputError(desc: "Given data has invalid bytes count.")
         }
     }
 
@@ -395,7 +395,7 @@ extension DefaultContractProtocol {
     @discardableResult
     public func callStatic(_ method: String, parameters: [Any], provider: Web3Provider) async throws -> [String: Any] {
         guard let address = address else {
-            throw Web3Error.inputError(desc: "address field is missing")
+            throw Web3Error.inputError(desc: "RPC failed: contract is missing an address.")
         }
         guard let data = self.method(method, parameters: parameters, extraData: nil) else {
             throw Web3Error.dataError
diff --git a/Sources/Web3Core/Utility/String+Extension.swift b/Sources/Web3Core/Utility/String+Extension.swift
index 16e6ff66b..778558166 100755
--- a/Sources/Web3Core/Utility/String+Extension.swift
+++ b/Sources/Web3Core/Utility/String+Extension.swift
@@ -137,7 +137,17 @@ extension String {
     }
 
     public var isHex: Bool {
-        stripHexPrefix().reduce(true, { $0 && $1.isHexDigit } )
+        var _str = self.trim()
+        if _str.isEmpty {
+            return false
+        }
+        _str = _str.stripHexPrefix()
+        for char in _str {
+            if !char.isHexDigit {
+                return false
+            }
+        }
+        return true
     }
 
     /// Splits a string into groups of `every` n characters, grouping from left-to-right by default. If `backwards` is true, right-to-left.
diff --git a/Tests/web3swiftTests/localTests/String+ExtensionTests.swift.swift b/Tests/web3swiftTests/localTests/String+ExtensionTests.swift.swift
new file mode 100644
index 000000000..1a6686178
--- /dev/null
+++ b/Tests/web3swiftTests/localTests/String+ExtensionTests.swift.swift
@@ -0,0 +1,31 @@
+//
+//  String+ExtensionTests.swift
+//
+//  Created by JeneaVranceanu on 26.11.2023.
+//
+
+import Foundation
+import XCTest
+
+class StringExtensionsTest: XCTestCase {
+
+    func testIsHex() throws {
+        XCTAssertTrue("0x".isHex)
+        XCTAssertTrue("0xF".isHex)
+        XCTAssertTrue("F".isHex)
+        XCTAssertTrue("0xFF".isHex)
+        XCTAssertTrue("0x0123456789abcdefABCDEF".isHex)
+        XCTAssertTrue("0123456789abcdefABCDEF".isHex)
+        XCTAssertTrue("0123456789abcdefABCDEF ".isHex)
+        XCTAssertTrue(" 0123456789abcdefABCDEF ".isHex)
+        XCTAssertTrue(" 0123456789abcdefABCDEF".isHex)
+
+        XCTAssertFalse("".isHex)
+        XCTAssertFalse("-".isHex)
+        XCTAssertFalse("xyz".isHex)
+        XCTAssertFalse("0xCAFEQ".isHex)
+        XCTAssertFalse("R0123456789abcdefABCDEF ".isHex)
+        XCTAssertFalse(" R0123456789abcdefABCDEF ".isHex)
+    }
+
+}