diff --git a/src/RemoteFileAPI/MessageHandlers.ts b/src/RemoteFileAPI/MessageHandlers.ts
index 2aecf10cd..966b7adaf 100644
--- a/src/RemoteFileAPI/MessageHandlers.ts
+++ b/src/RemoteFileAPI/MessageHandlers.ts
@@ -4,110 +4,170 @@ import { hasScriptExtension } from "../Paths/ScriptFilePath";
 import { GetServer, GetAllServers } from "../Server/AllServers";
 import {
   RFAMessage,
-  type FileData,
-  type FileContent,
   isFileServer,
   isFileLocation,
-  type FileLocation,
   isFileData,
-  type FileMetadata,
+  type FileData,
+  type FileLocation,
+  type FileServer,
 } from "./MessageDefinitions";
 
 import libSource from "../ScriptEditor/NetscriptDefinitions.d.ts?raw";
 import { saveObject } from "../SaveObject";
 import { Player } from "@player";
+import type { BaseServer } from "../Server/BaseServer";
+import type { ContentFilePath } from "../Paths/ContentFile";
 
-function error(errorMsg: string, { id }: RFAMessage): RFAMessage {
-  return new RFAMessage({ error: errorMsg, id: id });
+type SuccessResult<T> = { success: true; params: T };
+type FailureResult = { success: false; errorResponse: RFAMessage };
+export type ValidationResult<T> = SuccessResult<T> | FailureResult;
+
+function getErrorResponse(errorMsg: string, { id }: RFAMessage): RFAMessage {
+  return new RFAMessage({ error: errorMsg, id });
+}
+
+function validateParams<T>(validationFunction: (p: unknown) => p is T, request: RFAMessage): ValidationResult<T> {
+  if (!request.params) {
+    return { success: false, errorResponse: getErrorResponse("Missing params", request) };
+  }
+  if (!validationFunction(request.params)) {
+    return {
+      success: false,
+      errorResponse: getErrorResponse(`Invalid params: ${JSON.stringify(request.params)}`, request),
+    };
+  }
+  return { success: true, params: request.params };
+}
+
+function validateFilePathAndServerParams<T extends FileData | FileLocation>(
+  validationFunction: (p: unknown) => p is T,
+  request: RFAMessage,
+): { success: true; data: { filePath: ContentFilePath; server: BaseServer; params: T } } | FailureResult {
+  const validationResult = validateParams(validationFunction, request);
+  if (!validationResult.success) {
+    return validationResult;
+  }
+  const params = validationResult.params;
+  const filePath = resolveFilePath(params.filename);
+  if (!filePath) {
+    return { success: false, errorResponse: getErrorResponse(`Invalid file path: ${params.filename}`, request) };
+  }
+
+  if (!hasTextExtension(filePath) && !hasScriptExtension(filePath)) {
+    return {
+      success: false,
+      errorResponse: getErrorResponse(`Invalid file extension. Filename: ${params.filename}`, request),
+    };
+  }
+
+  const server = GetServer(params.server);
+  if (!server) {
+    return { success: false, errorResponse: getErrorResponse(`Invalid hostname: ${params.server}`, request) };
+  }
+
+  return { success: true, data: { filePath, server, params } };
+}
+
+function validateServerParams(
+  request: RFAMessage,
+): { success: true; data: { server: BaseServer; params: FileServer } } | FailureResult {
+  const validationResult = validateParams(isFileServer, request);
+  if (!validationResult.success) {
+    return validationResult;
+  }
+  const fileServer = validationResult.params;
+
+  const server = GetServer(fileServer.server);
+  if (!server) {
+    return { success: false, errorResponse: getErrorResponse(`Invalid hostname: ${fileServer.server}`, request) };
+  }
+
+  return { success: true, data: { server, params: fileServer } };
 }
 
 export const RFARequestHandler: Record<string, (message: RFAMessage) => RFAMessage | Promise<RFAMessage>> = {
   pushFile: function (msg: RFAMessage): RFAMessage {
-    if (!isFileData(msg.params)) return error("Misses parameters", msg);
-
-    const fileData: FileData = msg.params;
-    const filePath = resolveFilePath(fileData.filename);
-    if (!filePath) return error("Invalid file path", msg);
-
-    const server = GetServer(fileData.server);
-    if (!server) return error("Server hostname invalid", msg);
-
-    if (hasTextExtension(filePath) || hasScriptExtension(filePath)) {
-      server.writeToContentFile(filePath, fileData.content);
-      return new RFAMessage({ result: "OK", id: msg.id });
+    const validationResult = validateFilePathAndServerParams(isFileData, msg);
+    if (!validationResult.success) {
+      return validationResult.errorResponse;
     }
-    return error("Invalid file extension", msg);
+    const validationData = validationResult.data;
+
+    validationData.server.writeToContentFile(validationData.filePath, validationData.params.content);
+    return new RFAMessage({ result: "OK", id: msg.id });
   },
+
   getFile: function (msg: RFAMessage): RFAMessage {
-    if (!isFileLocation(msg.params)) return error("Message misses parameters", msg);
+    const validationResult = validateFilePathAndServerParams(isFileLocation, msg);
+    if (!validationResult.success) {
+      return validationResult.errorResponse;
+    }
+    const validationData = validationResult.data;
 
-    const fileData: FileLocation = msg.params;
-    const filePath = resolveFilePath(fileData.filename);
-    if (!filePath) return error("Invalid file path", msg);
+    const file = validationData.server.getContentFile(validationData.filePath);
+    if (!file) {
+      return getErrorResponse(`File does not exist. Filename: ${validationData.params.filename}`, msg);
+    }
 
-    const server = GetServer(fileData.server);
-    if (!server) return error("Server hostname invalid", msg);
-
-    if (!hasTextExtension(filePath) && !hasScriptExtension(filePath)) return error("Invalid file extension", msg);
-    const file = server.getContentFile(filePath);
-    if (!file) return error("File doesn't exist", msg);
     return new RFAMessage({ result: file.content, id: msg.id });
   },
 
   getFileMetadata: function (msg: RFAMessage): RFAMessage {
-    if (!isFileLocation(msg.params)) return error("Message misses parameters", msg);
+    const validationResult = validateFilePathAndServerParams(isFileLocation, msg);
+    if (!validationResult.success) {
+      return validationResult.errorResponse;
+    }
+    const validationData = validationResult.data;
 
-    const fileData: FileLocation = msg.params;
-    const filePath = resolveFilePath(fileData.filename);
-    if (!filePath) return error("Invalid file path", msg);
+    const file = validationData.server.getContentFile(validationData.filePath);
+    if (!file) {
+      return getErrorResponse(`File does not exist. Filename: ${validationData.params.filename}`, msg);
+    }
 
-    const server = GetServer(fileData.server);
-    if (!server) return error("Server hostname invalid", msg);
-
-    if (!hasTextExtension(filePath) && !hasScriptExtension(filePath)) return error("Invalid file extension", msg);
-    const file = server.getContentFile(filePath);
-    if (!file) return error("File doesn't exist", msg);
-
-    const result: FileMetadata = {
-      filename: file.filename,
-      ...file.metadata.plain(),
-    };
-    return new RFAMessage({ result: result, id: msg.id });
+    return new RFAMessage({
+      result: {
+        filename: file.filename,
+        ...file.metadata.plain(),
+      },
+      id: msg.id,
+    });
   },
 
   deleteFile: function (msg: RFAMessage): RFAMessage {
-    if (!isFileLocation(msg.params)) return error("Message misses parameters", msg);
+    const validationResult = validateFilePathAndServerParams(isFileLocation, msg);
+    if (!validationResult.success) {
+      return validationResult.errorResponse;
+    }
+    const validationData = validationResult.data;
 
-    const fileData: FileLocation = msg.params;
-    const filePath = resolveFilePath(fileData.filename);
-    if (!filePath) return error("Invalid filename", msg);
+    const resultOfRemovingFile = validationData.server.removeFile(validationData.filePath);
+    if (!resultOfRemovingFile.res) {
+      return getErrorResponse(resultOfRemovingFile.msg ?? "Failed", msg);
+    }
 
-    const server = GetServer(fileData.server);
-    if (!server) return error("Server hostname invalid", msg);
-
-    const result = server.removeFile(filePath);
-    if (result.res) return new RFAMessage({ result: "OK", id: msg.id });
-    return error(result.msg ?? "Failed", msg);
+    return new RFAMessage({ result: "OK", id: msg.id });
   },
 
   getFileNames: function (msg: RFAMessage): RFAMessage {
-    if (!isFileServer(msg.params)) return error("Message misses parameters", msg);
+    const validationResult = validateServerParams(msg);
+    if (!validationResult.success) {
+      return validationResult.errorResponse;
+    }
+    const validationData = validationResult.data;
 
-    const server = GetServer(msg.params.server);
-    if (!server) return error("Server hostname invalid", msg);
-
-    const fileNameList: string[] = [...server.textFiles.keys(), ...server.scripts.keys()];
+    const fileNameList = [...validationData.server.textFiles.keys(), ...validationData.server.scripts.keys()];
 
     return new RFAMessage({ result: fileNameList, id: msg.id });
   },
 
   getAllFiles: function (msg: RFAMessage): RFAMessage {
-    if (!isFileServer(msg.params)) return error("Message misses parameters", msg);
+    const validationResult = validateServerParams(msg);
+    if (!validationResult.success) {
+      return validationResult.errorResponse;
+    }
+    const validationData = validationResult.data;
 
-    const server = GetServer(msg.params.server);
-    if (!server) return error("Server hostname invalid", msg);
-
-    const fileList: FileContent[] = [...server.scripts, ...server.textFiles].map(([filename, file]) => ({
+    const fileList = [...validationData.server.scripts, ...validationData.server.textFiles].map(([filename, file]) => ({
       filename,
       content: file.content,
     }));
@@ -115,12 +175,13 @@ export const RFARequestHandler: Record<string, (message: RFAMessage) => RFAMessa
   },
 
   getAllFileMetadata: function (msg: RFAMessage): RFAMessage {
-    if (!isFileServer(msg.params)) return error("Message misses parameters", msg);
+    const validationResult = validateServerParams(msg);
+    if (!validationResult.success) {
+      return validationResult.errorResponse;
+    }
+    const validationData = validationResult.data;
 
-    const server = GetServer(msg.params.server);
-    if (!server) return error("Server hostname invalid", msg);
-
-    const fileList: FileMetadata[] = [...server.scripts, ...server.textFiles].map(([filename, file]) => ({
+    const fileList = [...validationData.server.scripts, ...validationData.server.textFiles].map(([filename, file]) => ({
       filename: filename,
       ...file.metadata.plain(),
     }));
@@ -128,19 +189,30 @@ export const RFARequestHandler: Record<string, (message: RFAMessage) => RFAMessa
   },
 
   calculateRam: function (msg: RFAMessage): RFAMessage {
-    if (!isFileLocation(msg.params)) return error("Message misses parameters", msg);
-    const fileData: FileLocation = msg.params;
-    const filePath = resolveFilePath(fileData.filename);
-    if (!filePath) return error("Invalid filename", msg);
+    const validationResult = validateFilePathAndServerParams(isFileLocation, msg);
+    if (!validationResult.success) {
+      return validationResult.errorResponse;
+    }
+    const validationData = validationResult.data;
 
-    const server = GetServer(fileData.server);
-    if (!server) return error("Server hostname invalid", msg);
+    // Validate filePath again. validateFilePathAndServerParams only checks if filePath is a text file or a script.
+    if (!hasScriptExtension(validationData.filePath)) {
+      return getErrorResponse(`File is not a script. Filename: ${validationData.params.filename}`, msg);
+    }
+
+    const script = validationData.server.scripts.get(validationData.filePath);
+    if (!script) {
+      return getErrorResponse(`File does not exist. Filename: ${validationData.params.filename}`, msg);
+    }
+
+    const ramUsage = script.getRamUsage(validationData.server.scripts);
+    if (!ramUsage) {
+      return getErrorResponse(
+        `Cannot calculate RAM usage of an invalid script. Filename: ${validationData.params.filename}`,
+        msg,
+      );
+    }
 
-    if (!hasScriptExtension(filePath)) return error("Filename isn't a script filename", msg);
-    const script = server.scripts.get(filePath);
-    if (!script) return error("File doesn't exist", msg);
-    const ramUsage = script.getRamUsage(server.scripts);
-    if (!ramUsage) return error("Ram cost could not be calculated", msg);
     return new RFAMessage({ result: ramUsage, id: msg.id });
   },