diff --git a/src/spider/CMakeLists.txt b/src/spider/CMakeLists.txt
index da1e3f23..a29fd233 100644
--- a/src/spider/CMakeLists.txt
+++ b/src/spider/CMakeLists.txt
@@ -68,6 +68,8 @@ set(SPIDER_WORKER_SOURCES
     worker/ChildPid.cpp
     worker/DllLoader.hpp
     worker/DllLoader.cpp
+    worker/WorkerErrorCode.cpp
+    worker/WorkerErrorCode.hpp
     worker/Process.hpp
     worker/Process.cpp
     worker/TaskExecutor.hpp
diff --git a/src/spider/worker/WorkerErrorCode.cpp b/src/spider/worker/WorkerErrorCode.cpp
new file mode 100644
index 00000000..735c35fa
--- /dev/null
+++ b/src/spider/worker/WorkerErrorCode.cpp
@@ -0,0 +1,40 @@
+#include "WorkerErrorCode.hpp"
+
+#include <string>
+#include <string_view>
+
+#include <ystdlib/error_handling/ErrorCode.hpp>
+
+namespace spider::worker {
+using WorkerErrorCategory = ystdlib::error_handling::ErrorCategory<WorkerErrorCodeEnum>;
+
+constexpr std::string_view cWorkerErrorCategoryName = "Worker Error Code";
+}  // namespace spider::worker
+
+template <>
+auto spider::worker::WorkerErrorCategory::name() const noexcept -> char const* {
+    return spider::worker::cWorkerErrorCategoryName.data();
+}
+
+template <>
+auto spider::worker::WorkerErrorCategory::message(spider::worker::WorkerErrorCodeEnum code) const
+        -> std::string {
+    switch (code) {
+        case spider::worker::WorkerErrorCodeEnum::Success:
+            return "Success";
+        case spider::worker::WorkerErrorCodeEnum::CmdLineArgumentInvalid:
+            return "Invalid command line argument";
+        case spider::worker::WorkerErrorCodeEnum::TaskArgumentInvalid:
+            return "Invalid task argument";
+        case spider::worker::WorkerErrorCodeEnum::TaskFailed:
+            return "Task failed";
+        case spider::worker::WorkerErrorCodeEnum::TaskOutputUnavailable:
+            return "Task output unavailable";
+        case spider::worker::WorkerErrorCodeEnum::TaskOutputInvalid:
+            return "Task output invalid";
+        case spider::worker::WorkerErrorCodeEnum::StorageError:
+            return "Storage error";
+        default:
+            return "Unknown error";
+    }
+}
diff --git a/src/spider/worker/WorkerErrorCode.hpp b/src/spider/worker/WorkerErrorCode.hpp
new file mode 100644
index 00000000..010919cd
--- /dev/null
+++ b/src/spider/worker/WorkerErrorCode.hpp
@@ -0,0 +1,25 @@
+#ifndef SPIDER_WORKER_ERROR_CODE_HPP
+#define SPIDER_WORKER_ERROR_CODE_HPP
+
+#include <cstdint>
+
+#include <ystdlib/error_handling/ErrorCode.hpp>
+
+namespace spider::worker {
+enum class WorkerErrorCodeEnum : uint8_t {
+    Success = 0,
+    CmdLineArgumentInvalid = 1,
+    TaskArgumentInvalid = 2,
+    TaskFailed = 3,
+    TaskOutputUnavailable = 4,
+    TaskOutputInvalid = 5,
+    // TODO: Move storage related errors to an ErrorCode in the storage namespace.
+    StorageError = 6,
+};
+
+using WorkerErrorCode = ystdlib::error_handling::ErrorCode<WorkerErrorCodeEnum>;
+}  // namespace spider::worker
+
+YSTDLIB_ERROR_HANDLING_MARK_AS_ERROR_CODE_ENUM(spider::worker::WorkerErrorCodeEnum);
+
+#endif
diff --git a/src/spider/worker/worker.cpp b/src/spider/worker/worker.cpp
index ade6ce6b..273405d1 100644
--- a/src/spider/worker/worker.cpp
+++ b/src/spider/worker/worker.cpp
@@ -32,6 +32,11 @@
 #include <fmt/format.h>
 #include <spdlog/sinks/stdout_color_sinks.h>  // IWYU pragma: keep
 #include <spdlog/spdlog.h>
+// Temporarily disable quickcpplib to include valgrind headers to avoid
+// conflicts with abseil valgrind headers, until the issue is resolved at
+// https://github.com/y-scope/ystdlib-cpp/issues/59.
+#undef QUICKCPPLIB_ENABLE_VALGRIND
+#include <ystdlib/error_handling/Result.hpp>
 
 #include <spider/core/Data.hpp>
 #include <spider/core/Driver.hpp>
@@ -49,6 +54,7 @@
 #include <spider/worker/ChildPid.hpp>
 #include <spider/worker/TaskExecutor.hpp>
 #include <spider/worker/WorkerClient.hpp>
+#include <spider/worker/WorkerErrorCode.hpp>
 
 constexpr int cCmdArgParseErr = 1;
 constexpr int cSignalHandleErr = 2;
@@ -180,7 +186,7 @@ fetch_task(spider::worker::WorkerClient& client, std::optional<boost::uuids::uui
     return std::nullopt;
 }
 
-/*
+/**
  * Sets up a task by fetching the task metadata from storage and creating argument buffers from task
  * inputs.
  *
@@ -189,14 +195,15 @@ fetch_task(spider::worker::WorkerClient& client, std::optional<boost::uuids::uui
  * @param instance The task instance to set up.
  * @param task Output parameter to store the fetched task details.
  * @return  A vector of buffers containing the serialized arguments of the task.
- * @return std::nullopt if any failure occurs.
+ * @return WorkerErrorCode if any failure occurs.
  */
 auto setup_task(
         std::shared_ptr<spider::core::StorageFactory> const& storage_factory,
         std::shared_ptr<spider::core::MetadataStorage> const& metadata_store,
         spider::core::TaskInstance const& instance,
         spider::core::Task& task
-) -> std::optional<std::vector<msgpack::sbuffer>> {
+) -> ystdlib::error_handling::
+        Result<std::vector<msgpack::sbuffer>, spider::worker::WorkerErrorCode> {
     std::variant<std::unique_ptr<spider::core::StorageConnection>, spider::core::StorageErr>
             conn_result = storage_factory->provide_storage_connection();
     if (std::holds_alternative<spider::core::StorageErr>(conn_result)) {
@@ -204,7 +211,7 @@ auto setup_task(
                 "Failed to connect to storage: {}",
                 std::get<spider::core::StorageErr>(conn_result).description
         );
-        return std::nullopt;
+        return spider::worker::WorkerErrorCodeEnum::StorageError;
     }
     std::unique_ptr<spider::core::StorageConnection> conn
             = std::move(std::get<std::unique_ptr<spider::core::StorageConnection>>(conn_result));
@@ -212,21 +219,30 @@ auto setup_task(
     spider::core::StorageErr const err = metadata_store->get_task(*conn, instance.task_id, &task);
     if (!err.success()) {
         spdlog::error("Failed to fetch task detail: {}", err.description);
-        return std::nullopt;
+        return spider::worker::WorkerErrorCodeEnum::StorageError;
     }
 
     std::optional<std::vector<msgpack::sbuffer>> optional_arg_buffers = task.get_arg_buffers();
     if (!optional_arg_buffers.has_value()) {
         spdlog::error("Failed to fetch task arguments");
         metadata_store->task_fail(*conn, instance, fmt::format("Failed to fetch task arguments"));
-        return std::nullopt;
+        return spider::worker::WorkerErrorCodeEnum::TaskArgumentInvalid;
     }
-    return optional_arg_buffers;
+    return std::move(optional_arg_buffers.value());
 }
 
+/**
+ * Parses the task outputs from the result buffers.
+ *
+ * @param task The task that was executed.
+ * @param result_buffers The result buffers containing the outputs.
+ * @return A vector of TaskOutput objects if parsing is successful.
+ * @return WorkerErrorCode::TaskOutputInvalid if any failure occurs.
+ */
 auto
 parse_outputs(spider::core::Task const& task, std::vector<msgpack::sbuffer> const& result_buffers)
-        -> std::optional<std::vector<spider::core::TaskOutput>> {
+        -> ystdlib::error_handling::
+                Result<std::vector<spider::core::TaskOutput>, spider::worker::WorkerErrorCode> {
     std::vector<spider::core::TaskOutput> outputs;
     outputs.reserve(task.get_num_outputs());
     for (size_t i = 0; i < task.get_num_outputs(); ++i) {
@@ -244,7 +260,7 @@ parse_outputs(spider::core::Task const& task, std::vector<msgpack::sbuffer> cons
                         "Task {} failed to parse result as data id",
                         task.get_function_name()
                 );
-                return std::nullopt;
+                return spider::worker::WorkerErrorCodeEnum::TaskOutputInvalid;
             }
         } else {
             msgpack::sbuffer const& buffer = result_buffers[i];
@@ -263,7 +279,8 @@ parse_outputs(spider::core::Task const& task, std::vector<msgpack::sbuffer> cons
  * @param instance Task instance that was executed.
  * @param task The task that was executed.
  * @param executor The executor that ran the task.
- * @return true if results were successfully handled, false if any errors occurred.
+ * @return ystdlib::error_handling::success() if successful.
+ * @return WorkerErrorCode if any failure occurs.
  */
 auto handle_executor_result(
         std::shared_ptr<spider::core::StorageFactory> const& storage_factory,
@@ -271,7 +288,7 @@ auto handle_executor_result(
         spider::core::TaskInstance const& instance,
         spider::core::Task const& task,
         spider::worker::TaskExecutor& executor
-) -> bool {
+) -> ystdlib::error_handling::Result<void, spider::worker::WorkerErrorCode> {
     std::variant<std::unique_ptr<spider::core::StorageConnection>, spider::core::StorageErr>
             conn_result = storage_factory->provide_storage_connection();
     if (std::holds_alternative<spider::core::StorageErr>(conn_result)) {
@@ -279,7 +296,7 @@ auto handle_executor_result(
                 "Failed to connect to storage: {}",
                 std::get<spider::core::StorageErr>(conn_result).description
         );
-        return false;
+        return spider::worker::WorkerErrorCodeEnum::StorageError;
     }
     auto conn = std::move(std::get<std::unique_ptr<spider::core::StorageConnection>>(conn_result));
 
@@ -290,7 +307,7 @@ auto handle_executor_result(
                 instance,
                 fmt::format("Task {} failed", task.get_function_name())
         );
-        return false;
+        return spider::worker::WorkerErrorCodeEnum::TaskFailed;
     }
 
     // Parse result
@@ -303,12 +320,14 @@ auto handle_executor_result(
                 instance,
                 fmt::format("Task {} failed to parse result into buffers", task.get_function_name())
         );
-        return false;
+        return spider::worker::WorkerErrorCodeEnum::TaskOutputUnavailable;
     }
     std::vector<msgpack::sbuffer> const& result_buffers = optional_result_buffers.value();
-    std::optional<std::vector<spider::core::TaskOutput>> const optional_outputs
+    ystdlib::error_handling::Result<
+            std::vector<spider::core::TaskOutput>,
+            spider::worker::WorkerErrorCode> const output_result
             = parse_outputs(task, result_buffers);
-    if (!optional_outputs.has_value()) {
+    if (!output_result.has_value()) {
         metadata_store->task_fail(
                 *conn,
                 instance,
@@ -317,10 +336,10 @@ auto handle_executor_result(
                         task.get_function_name()
                 )
         );
-        return false;
+        return output_result.error();
     }
 
-    std::vector<spider::core::TaskOutput> const& outputs = optional_outputs.value();
+    std::vector<spider::core::TaskOutput> const& outputs = output_result.value();
     // Submit result
     spdlog::debug("Submitting result for task {}", boost::uuids::to_string(task.get_id()));
     spider::core::StorageErr err;
@@ -336,9 +355,9 @@ auto handle_executor_result(
     }
     if (!err.success()) {
         spdlog::error("Submit task {} fails: {}", task.get_function_name(), err.description);
-        return false;
+        return spider::worker::WorkerErrorCodeEnum::StorageError;
     }
-    return true;
+    return ystdlib::error_handling::success();
 }
 
 // NOLINTBEGIN(clang-analyzer-unix.BlockInCriticalSection)
@@ -365,15 +384,16 @@ auto task_loop(
         spdlog::debug("Fetched task {}", boost::uuids::to_string(task_id));
         // Fetch task detail from metadata storage
         spider::core::Task task{""};
-
-        std::optional<std::vector<msgpack::sbuffer>> optional_arg_buffers
+        ystdlib::error_handling::
+                Result<std::vector<msgpack::sbuffer>, spider::worker::WorkerErrorCode>
+                        arg_buffers_result
                 = setup_task(storage_factory, metadata_store, instance, task);
-        if (!optional_arg_buffers.has_value()) {
+        if (!arg_buffers_result.has_value()) {
             spdlog::error("Failed to setup task {}", task.get_function_name());
             fail_task_id = task.get_id();
             continue;
         }
-        std::vector<msgpack::sbuffer> const& arg_buffers = optional_arg_buffers.value();
+        std::vector<msgpack::sbuffer> const& arg_buffers = arg_buffers_result.value();
 
         // Execute task
         spider::worker::TaskExecutor executor{
@@ -397,9 +417,9 @@ auto task_loop(
         context.run();
         executor.wait();
 
-        spider::core::ChildPid::set_pid(0);
-
-        if (handle_executor_result(storage_factory, metadata_store, instance, task, executor)) {
+        if (handle_executor_result(storage_factory, metadata_store, instance, task, executor)
+                    .has_value())
+        {
             fail_task_id = std::nullopt;
         } else {
             fail_task_id = task.get_id();