diff --git a/server/src/http-interfaces.ts b/server/src/http-interfaces.ts
index d1d64db01..49d9bdc7a 100644
--- a/server/src/http-interfaces.ts
+++ b/server/src/http-interfaces.ts
@@ -110,7 +110,7 @@ export class HttpResponseImpl implements HttpResponse {
                 this.res.end();
             }
             catch (e) {
-                this.res.destroy(e);
+                this.res.destroy(e as Error);
             }
             finally {
                 peer.kill();
diff --git a/server/src/level.ts b/server/src/level.ts
index 1862d276c..f5524e6f5 100644
--- a/server/src/level.ts
+++ b/server/src/level.ts
@@ -16,7 +16,7 @@ function createLevelDocument(documentConstructor: any, json: any) {
 }
 
 export class WrappedLevel extends Level<string, string | number> {
-    curId: number;
+    curId!: number;
 
     override async open(): Promise<void>;
     override async open(options?: OpenOptions): Promise<void> {
diff --git a/server/src/plugin/plugin-http.ts b/server/src/plugin/plugin-http.ts
index 6f5384232..8d4a4c13e 100644
--- a/server/src/plugin/plugin-http.ts
+++ b/server/src/plugin/plugin-http.ts
@@ -38,7 +38,7 @@ export abstract class PluginHttp<T> {
 
     abstract handleEngineIOEndpoint(req: Request, res: ServerResponse, endpointRequest: HttpRequest, pluginData: T): void;
     abstract handleRequestEndpoint(req: Request, res: Response, endpointRequest: HttpRequest, pluginData: T): void;
-    abstract getEndpointPluginData(req: Request, endpoint: string, isUpgrade: boolean, isEngineIOEndpoint: boolean): Promise<T>;
+    abstract getEndpointPluginData(req: Request, endpoint: string, isUpgrade: boolean, isEngineIOEndpoint: boolean): Promise<T | undefined>;
     abstract handleWebSocket(endpoint: string, httpRequest: HttpRequest, ws: WebSocket, pluginData: T): Promise<void>;
     abstract checkUpgrade(req: Request, res: Response, pluginData: T): void;
 
@@ -129,7 +129,7 @@ export abstract class PluginHttp<T> {
             catch (e) {
                 res.header('Content-Type', 'text/plain');
                 res.status(500);
-                res.send(e.toString());
+                res.send((e as Error).toString());
                 console.error(e);
             }
         }
@@ -140,7 +140,7 @@ export abstract class PluginHttp<T> {
             catch (e) {
                 res.header('Content-Type', 'text/plain');
                 res.status(500);
-                res.send(e.toString());
+                res.send((e as Error).toString());
                 console.error(e);
             }
         }
diff --git a/server/src/rpc.ts b/server/src/rpc.ts
index 9e481aead..039731e91 100644
--- a/server/src/rpc.ts
+++ b/server/src/rpc.ts
@@ -293,7 +293,7 @@ export class RpcPeer {
     finalizers = new FinalizationRegistry(entry => this.finalize(entry as LocalProxiedEntry));
     nameDeserializerMap = new Map<string, RpcSerializer>();
     onProxyTypeSerialization = new Map<string, (value: any) => void>();
-    onProxySerialization: (value: any) => {
+    onProxySerialization?: (value: any) => {
         proxyId: string;
         properties: any;
     };
@@ -301,7 +301,7 @@ export class RpcPeer {
     transportSafeArgumentTypes = RpcPeer.getDefaultTransportSafeArgumentTypes();
     killed: Promise<string>;
     killedSafe: Promise<void>;
-    killedDeferred: Deferred;
+    killedDeferred!: Deferred;
     tags: any = {};
     yieldedAsyncIterators = new Set<AsyncGenerator>();
 
diff --git a/server/src/state.ts b/server/src/state.ts
index 5c32aec8e..23e7f0862 100644
--- a/server/src/state.ts
+++ b/server/src/state.ts
@@ -227,7 +227,7 @@ export class ScryptedStateManager extends EventRegistry {
                 }
                 catch (e) {
                     logger.log('e', 'Refresh failed');
-                    logger.log('e', e.toString());
+                    logger.log('e', (e as Error).toString());
                 }
                 finally {
                     delete this.refreshThrottles[id];
diff --git a/server/src/threading.ts b/server/src/threading.ts
index ad11729c2..8455cd909 100644
--- a/server/src/threading.ts
+++ b/server/src/threading.ts
@@ -39,7 +39,7 @@ export async function newThread<T>(...args: any[]): Promise<T> {
                 thread_worker_threads.parentPort!.postMessage(thread_v8.serialize(message));
             }
             catch (e) {
-                reject?.(e);
+                reject?.(e as Error);
             }
         });
         mainPeer.transportSafeArgumentTypes.add(Buffer.name);
@@ -79,7 +79,7 @@ export async function newThread<T>(...args: any[]): Promise<T> {
             worker.postMessage(v8.serialize(message));
         }
         catch (e) {
-            reject?.(e);
+            reject?.(e as Error);
         }
     });
     threadPeer.transportSafeArgumentTypes.add(Buffer.name);
diff --git a/server/src/usertoken.ts b/server/src/usertoken.ts
index 748643e19..0972e65ea 100644
--- a/server/src/usertoken.ts
+++ b/server/src/usertoken.ts
@@ -2,7 +2,7 @@ export const ONE_DAY_MILLISECONDS = 86400000;
 export const ONE_YEAR_MILLISECONDS = ONE_DAY_MILLISECONDS * 365;
 
 export class UserToken {
-    constructor(public username: string, public aclId: string, public timestamp = Date.now(), public duration = ONE_DAY_MILLISECONDS) {
+    constructor(public username: string, public aclId?: string, public timestamp = Date.now(), public duration = ONE_DAY_MILLISECONDS) {
     }
 
     static validateToken(token: string): UserToken {