diff --git a/apps/browser/src/auth/popup/account-switching/services/account-switcher.service.ts b/apps/browser/src/auth/popup/account-switching/services/account-switcher.service.ts
index 7bb12fc260..99d2c83283 100644
--- a/apps/browser/src/auth/popup/account-switching/services/account-switcher.service.ts
+++ b/apps/browser/src/auth/popup/account-switching/services/account-switcher.service.ts
@@ -160,7 +160,7 @@ export class AccountSwitcherService {
             throwError(() => new Error(AccountSwitcherService.incompleteAccountSwitchError)),
         }),
       ),
-    ).catch((err) => {
+    ).catch((err): any => {
       if (
         err instanceof Error &&
         err.message === AccountSwitcherService.incompleteAccountSwitchError
diff --git a/apps/browser/src/autofill/services/autofill.service.ts b/apps/browser/src/autofill/services/autofill.service.ts
index 0e238d14d2..ca735f8f4f 100644
--- a/apps/browser/src/autofill/services/autofill.service.ts
+++ b/apps/browser/src/autofill/services/autofill.service.ts
@@ -161,7 +161,7 @@ export default class AutofillService implements AutofillServiceInterface {
 
     // Create a timeout observable that emits an empty array if pageDetailsFromTab$ hasn't emitted within 1 second.
     const pageDetailsTimeout$ = timer(1000).pipe(
-      map(() => []),
+      map((): any => []),
       takeUntil(sharedPageDetailsFromTab$),
     );
 
diff --git a/apps/browser/src/platform/popup/services/browser-router.service.ts b/apps/browser/src/platform/popup/services/browser-router.service.ts
index 2d449b8a0f..e1de1fdd29 100644
--- a/apps/browser/src/platform/popup/services/browser-router.service.ts
+++ b/apps/browser/src/platform/popup/services/browser-router.service.ts
@@ -21,9 +21,7 @@ export class BrowserRouterService {
           child = child.firstChild;
         }
 
-        // TODO: Eslint upgrade. Please resolve this since the ?? does nothing
-        // eslint-disable-next-line no-constant-binary-expression
-        const updateUrl = !child?.data?.doNotSaveUrl ?? true;
+        const updateUrl = !child?.data?.doNotSaveUrl;
 
         if (updateUrl) {
           this.setPreviousUrl(event.url);
diff --git a/apps/browser/src/platform/popup/view-cache/popup-router-cache.service.ts b/apps/browser/src/platform/popup/view-cache/popup-router-cache.service.ts
index b545618c0c..2e9746642f 100644
--- a/apps/browser/src/platform/popup/view-cache/popup-router-cache.service.ts
+++ b/apps/browser/src/platform/popup/view-cache/popup-router-cache.service.ts
@@ -62,9 +62,7 @@ export class PopupRouterCacheService {
             child = child.firstChild;
           }
 
-          // TODO: Eslint upgrade. Please resolve this since the ?? does nothing
-          // eslint-disable-next-line no-constant-binary-expression
-          return !child?.data?.doNotSaveUrl ?? true;
+          return !child?.data?.doNotSaveUrl;
         }),
         switchMap((event) => this.push(event.url)),
       )
diff --git a/apps/browser/src/vault/popup/services/vault-popup-list-filters.service.spec.ts b/apps/browser/src/vault/popup/services/vault-popup-list-filters.service.spec.ts
index eecd1f2fd6..692e21d008 100644
--- a/apps/browser/src/vault/popup/services/vault-popup-list-filters.service.spec.ts
+++ b/apps/browser/src/vault/popup/services/vault-popup-list-filters.service.spec.ts
@@ -761,11 +761,13 @@ function createSeededVaultPopupListFiltersService(
   const collectionServiceMock = {
     decryptedCollections$: () => seededCollections$,
     getAllNested: () =>
-      seededCollections$.value.map((c) => ({
-        children: [],
-        node: c,
-        parent: null,
-      })),
+      seededCollections$.value.map(
+        (c): TreeNode<CollectionView> => ({
+          children: [],
+          node: c,
+          parent: null as any,
+        }),
+      ),
   } as any;
 
   const folderServiceMock = {
diff --git a/apps/desktop/src/vault/app/vault/vault-v2.component.ts b/apps/desktop/src/vault/app/vault/vault-v2.component.ts
index 3fdb14aa15..aa631c44c6 100644
--- a/apps/desktop/src/vault/app/vault/vault-v2.component.ts
+++ b/apps/desktop/src/vault/app/vault/vault-v2.component.ts
@@ -290,7 +290,7 @@ export class VaultV2Component<C extends CipherViewLike>
                 ) {
                   const value = await firstValueFrom(
                     this.totpService.getCode$(this.cipher.login.totp),
-                  ).catch(() => null);
+                  ).catch((): any => null);
                   if (value) {
                     this.copyValue(this.cipher, value.code, "verificationCodeTotp", "TOTP");
                   }
@@ -329,7 +329,7 @@ export class VaultV2Component<C extends CipherViewLike>
 
     this.activeUserId = await firstValueFrom(
       this.accountService.activeAccount$.pipe(getUserId),
-    ).catch(() => null);
+    ).catch((): any => null);
 
     if (this.activeUserId) {
       this.cipherService
@@ -448,7 +448,7 @@ export class VaultV2Component<C extends CipherViewLike>
     const dialogRef = AttachmentsV2Component.open(this.dialogService, {
       cipherId: this.cipherId as CipherId,
     });
-    const result = await firstValueFrom(dialogRef.closed).catch(() => null);
+    const result = await firstValueFrom(dialogRef.closed).catch((): any => null);
     if (
       result?.action === AttachmentDialogResult.Removed ||
       result?.action === AttachmentDialogResult.Uploaded
@@ -574,7 +574,7 @@ export class VaultV2Component<C extends CipherViewLike>
             click: async () => {
               const value = await firstValueFrom(
                 this.totpService.getCode$(cipher.login.totp),
-              ).catch(() => null);
+              ).catch((): any => null);
               if (value) {
                 this.copyValue(cipher, value.code, "verificationCodeTotp", "TOTP");
               }
@@ -617,7 +617,7 @@ export class VaultV2Component<C extends CipherViewLike>
   async buildFormConfig(action: CipherFormMode) {
     this.config = await this.formConfigService
       .buildConfig(action, this.cipherId as CipherId, this.addType)
-      .catch(() => null);
+      .catch((): any => null);
   }
 
   async editCipher(cipher: CipherView) {
diff --git a/apps/web/src/app/billing/services/subscription-pricing.service.ts b/apps/web/src/app/billing/services/subscription-pricing.service.ts
index fad797bed5..82ec9f180b 100644
--- a/apps/web/src/app/billing/services/subscription-pricing.service.ts
+++ b/apps/web/src/app/billing/services/subscription-pricing.service.ts
@@ -110,7 +110,7 @@ export class SubscriptionPricingService {
   );
 
   private free$: Observable<BusinessSubscriptionPricingTier> = this.plansResponse$.pipe(
-    map((plans) => {
+    map((plans): BusinessSubscriptionPricingTier => {
       const freePlan = plans.data.find((plan) => plan.type === PlanType.Free)!;
 
       return {
@@ -215,20 +215,22 @@ export class SubscriptionPricingService {
   );
 
   private custom$: Observable<BusinessSubscriptionPricingTier> = this.plansResponse$.pipe(
-    map(() => ({
-      id: BusinessSubscriptionPricingTierIds.Custom,
-      name: this.i18nService.t("planNameCustom"),
-      description: this.i18nService.t("planDescCustom"),
-      availableCadences: [],
-      passwordManager: {
-        type: "custom",
-        features: [
-          this.featureTranslations.strengthenCybersecurity(),
-          this.featureTranslations.boostProductivity(),
-          this.featureTranslations.seamlessIntegration(),
-        ],
-      },
-    })),
+    map(
+      (): BusinessSubscriptionPricingTier => ({
+        id: BusinessSubscriptionPricingTierIds.Custom,
+        name: this.i18nService.t("planNameCustom"),
+        description: this.i18nService.t("planDescCustom"),
+        availableCadences: [],
+        passwordManager: {
+          type: "custom",
+          features: [
+            this.featureTranslations.strengthenCybersecurity(),
+            this.featureTranslations.boostProductivity(),
+            this.featureTranslations.seamlessIntegration(),
+          ],
+        },
+      }),
+    ),
   );
 
   private showUnexpectedErrorToast() {
diff --git a/apps/web/src/app/core/router.service.ts b/apps/web/src/app/core/router.service.ts
index 603c171e95..7a2e53a374 100644
--- a/apps/web/src/app/core/router.service.ts
+++ b/apps/web/src/app/core/router.service.ts
@@ -75,9 +75,7 @@ export class RouterService {
         const titleId: string = child?.snapshot?.data?.titleId;
         const rawTitle: string = child?.snapshot?.data?.title;
 
-        // TODO: Eslint upgrade. Please resolve this since the ?? does nothing
-        // eslint-disable-next-line no-constant-binary-expression
-        const updateUrl = !child?.snapshot?.data?.doNotSaveUrl ?? true;
+        const updateUrl = !child?.snapshot?.data?.doNotSaveUrl;
 
         if (titleId != null || rawTitle != null) {
           const newTitle = rawTitle != null ? rawTitle : i18nService.t(titleId);
diff --git a/apps/web/src/app/layouts/product-switcher/shared/product-switcher.service.ts b/apps/web/src/app/layouts/product-switcher/shared/product-switcher.service.ts
index ba86e9fed2..95acf4447e 100644
--- a/apps/web/src/app/layouts/product-switcher/shared/product-switcher.service.ts
+++ b/apps/web/src/app/layouts/product-switcher/shared/product-switcher.service.ts
@@ -87,7 +87,7 @@ export class ProductSwitcherService {
       startWith(null), // Start with a null event to trigger the initial combineLatest
       filter((e) => e instanceof NavigationEnd || e instanceof NavigationStart || e === null),
     ),
-  ]).pipe(map(() => null));
+  ]).pipe(map((): any => null));
 
   constructor(
     private organizationService: OrganizationService,
diff --git a/apps/web/src/app/vault/components/vault-items/vault-items.component.ts b/apps/web/src/app/vault/components/vault-items/vault-items.component.ts
index a5bcb91571..82ddda6611 100644
--- a/apps/web/src/app/vault/components/vault-items/vault-items.component.ts
+++ b/apps/web/src/app/vault/components/vault-items/vault-items.component.ts
@@ -17,6 +17,7 @@ import {
   CipherViewLikeUtils,
 } from "@bitwarden/common/vault/utils/cipher-view-like-utils";
 import { SortDirection, TableDataSource } from "@bitwarden/components";
+import { OrganizationId } from "@bitwarden/sdk-internal";
 
 import { GroupView } from "../../../admin-console/organizations/core";
 
@@ -579,7 +580,7 @@ export class VaultItemsComponent<C extends CipherViewLike> {
       .every(({ cipher }) => cipher?.edit && cipher?.viewPassword);
   }
 
-  private getUniqueOrganizationIds(): Set<string> {
+  private getUniqueOrganizationIds(): Set<string | [] | OrganizationId> {
     return new Set(this.selection.selected.flatMap((i) => i.cipher?.organizationId ?? []));
   }
 
diff --git a/bitwarden_license/bit-web/src/app/secrets-manager/projects/project/project-people.component.ts b/bitwarden_license/bit-web/src/app/secrets-manager/projects/project/project-people.component.ts
index 13f8092055..ec7397a22a 100644
--- a/bitwarden_license/bit-web/src/app/secrets-manager/projects/project/project-people.component.ts
+++ b/bitwarden_license/bit-web/src/app/secrets-manager/projects/project/project-people.component.ts
@@ -41,7 +41,7 @@ export class ProjectPeopleComponent implements OnInit, OnDestroy {
         return convertToAccessPolicyItemViews(policies);
       }),
     ),
-    catchError(async () => {
+    catchError(async (): Promise<any> => {
       this.logService.info("Error fetching project people access policies.");
       await this.router.navigate(["/sm", this.organizationId, "projects"]);
       return undefined;
diff --git a/libs/auth/src/common/login-strategies/webauthn-login.strategy.spec.ts b/libs/auth/src/common/login-strategies/webauthn-login.strategy.spec.ts
index f5ba2d0be2..25ae8a31ef 100644
--- a/libs/auth/src/common/login-strategies/webauthn-login.strategy.spec.ts
+++ b/libs/auth/src/common/login-strategies/webauthn-login.strategy.spec.ts
@@ -75,7 +75,7 @@ describe("WebAuthnLoginStrategy", () => {
 
     // We must do this to make the mocked classes available for all the
     // assertCredential(...) tests.
-    global.PublicKeyCredential = MockPublicKeyCredential;
+    global.PublicKeyCredential = MockPublicKeyCredential as any;
     global.AuthenticatorAssertionResponse = MockAuthenticatorAssertionResponse;
   });
 
@@ -397,4 +397,8 @@ export class MockPublicKeyCredential implements PublicKeyCredential {
   static isUserVerifyingPlatformAuthenticatorAvailable(): Promise<boolean> {
     return Promise.resolve(false);
   }
+
+  toJSON() {
+    throw new Error("Method not implemented.");
+  }
 }
diff --git a/libs/common/src/auth/services/webauthn-login/webauthn-login.service.spec.ts b/libs/common/src/auth/services/webauthn-login/webauthn-login.service.spec.ts
index 56aa1139cd..b848cb2f90 100644
--- a/libs/common/src/auth/services/webauthn-login/webauthn-login.service.spec.ts
+++ b/libs/common/src/auth/services/webauthn-login/webauthn-login.service.spec.ts
@@ -38,7 +38,7 @@ describe("WebAuthnLoginService", () => {
 
     // We must do this to make the mocked classes available for all the
     // assertCredential(...) tests.
-    global.PublicKeyCredential = MockPublicKeyCredential;
+    global.PublicKeyCredential = MockPublicKeyCredential as any;
     global.AuthenticatorAssertionResponse = MockAuthenticatorAssertionResponse;
 
     // Save the original navigator
@@ -316,6 +316,10 @@ class MockPublicKeyCredential implements PublicKeyCredential {
   static isUserVerifyingPlatformAuthenticatorAvailable(): Promise<boolean> {
     return Promise.resolve(false);
   }
+
+  toJSON() {
+    throw new Error("Method not implemented.");
+  }
 }
 
 function buildCredentialAssertionOptions(): WebAuthnLoginCredentialAssertionOptionsView {
diff --git a/libs/common/src/vault/utils/observable-utilities.ts b/libs/common/src/vault/utils/observable-utilities.ts
index cdec51fc95..025da8a36f 100644
--- a/libs/common/src/vault/utils/observable-utilities.ts
+++ b/libs/common/src/vault/utils/observable-utilities.ts
@@ -30,7 +30,7 @@ export function perUserCache$<TValue>(
         create(userId),
         clearBuffer$.pipe(
           filter((clearId) => clearId === userId || clearId === null),
-          map(() => null),
+          map((): any => null),
         ),
       ).pipe(shareReplay({ bufferSize: 1, refCount: false }));
       cache.set(userId, observable);
diff --git a/libs/vault/src/cipher-form/components/additional-options/additional-options-section.component.spec.ts b/libs/vault/src/cipher-form/components/additional-options/additional-options-section.component.spec.ts
index 16588f9280..6d0266dd0f 100644
--- a/libs/vault/src/cipher-form/components/additional-options/additional-options-section.component.spec.ts
+++ b/libs/vault/src/cipher-form/components/additional-options/additional-options-section.component.spec.ts
@@ -28,7 +28,7 @@ describe("AdditionalOptionsSectionComponent", () => {
   let passwordRepromptService: MockProxy<PasswordRepromptService>;
   let passwordRepromptEnabled$: BehaviorSubject<boolean>;
 
-  const getInitialCipherView = jest.fn(() => null);
+  const getInitialCipherView = jest.fn((): any => null);
   const formStatusChange$ = new BehaviorSubject<"enabled" | "disabled">("enabled");
 
   beforeEach(async () => {
diff --git a/libs/vault/src/cipher-form/components/autofill-options/autofill-options.component.spec.ts b/libs/vault/src/cipher-form/components/autofill-options/autofill-options.component.spec.ts
index 3654dc4fe1..afbf1d8664 100644
--- a/libs/vault/src/cipher-form/components/autofill-options/autofill-options.component.spec.ts
+++ b/libs/vault/src/cipher-form/components/autofill-options/autofill-options.component.spec.ts
@@ -34,7 +34,7 @@ describe("AutofillOptionsComponent", () => {
   let domainSettingsService: MockProxy<DomainSettingsService>;
   let autofillSettingsService: MockProxy<AutofillSettingsServiceAbstraction>;
   let platformUtilsService: MockProxy<PlatformUtilsService>;
-  const getInitialCipherView = jest.fn(() => null);
+  const getInitialCipherView = jest.fn((): any => null);
   const formStatusChange$ = new BehaviorSubject<"enabled" | "disabled">("enabled");
 
   beforeEach(async () => {
diff --git a/libs/vault/src/cipher-form/components/card-details-section/card-details-section.component.spec.ts b/libs/vault/src/cipher-form/components/card-details-section/card-details-section.component.spec.ts
index 32baad189c..9233f1fa40 100644
--- a/libs/vault/src/cipher-form/components/card-details-section/card-details-section.component.spec.ts
+++ b/libs/vault/src/cipher-form/components/card-details-section/card-details-section.component.spec.ts
@@ -20,7 +20,7 @@ describe("CardDetailsSectionComponent", () => {
   let registerChildFormSpy: jest.SpyInstance;
   let patchCipherSpy: jest.SpyInstance;
 
-  const getInitialCipherView = jest.fn(() => null);
+  const getInitialCipherView = jest.fn((): any => null);
 
   beforeEach(async () => {
     cipherFormProvider = mock<CipherFormContainer>({ getInitialCipherView });
diff --git a/libs/vault/src/cipher-form/components/cipher-form.component.spec.ts b/libs/vault/src/cipher-form/components/cipher-form.component.spec.ts
index 970e6b1fb9..ac384ee3fd 100644
--- a/libs/vault/src/cipher-form/components/cipher-form.component.spec.ts
+++ b/libs/vault/src/cipher-form/components/cipher-form.component.spec.ts
@@ -37,7 +37,7 @@ describe("CipherFormComponent", () => {
           provide: CipherFormCacheService,
           useValue: { init: jest.fn(), getCachedCipherView: jest.fn() },
         },
-        { provide: ViewCacheService, useValue: { signal: jest.fn(() => () => null) } },
+        { provide: ViewCacheService, useValue: { signal: jest.fn(() => (): any => null) } },
         { provide: ConfigService, useValue: mock<ConfigService>() },
       ],
     }).compileComponents();
diff --git a/libs/vault/src/cipher-form/components/login-details-section/login-details-section.component.spec.ts b/libs/vault/src/cipher-form/components/login-details-section/login-details-section.component.spec.ts
index b07a50fd38..d6fe8a6492 100644
--- a/libs/vault/src/cipher-form/components/login-details-section/login-details-section.component.spec.ts
+++ b/libs/vault/src/cipher-form/components/login-details-section/login-details-section.component.spec.ts
@@ -42,7 +42,7 @@ describe("LoginDetailsSectionComponent", () => {
   let configService: MockProxy<ConfigService>;
 
   const collect = jest.fn().mockResolvedValue(null);
-  const getInitialCipherView = jest.fn(() => null);
+  const getInitialCipherView = jest.fn((): any => null);
 
   beforeEach(async () => {
     getInitialCipherView.mockClear();
diff --git a/package-lock.json b/package-lock.json
index afcedcfaf7..d5c0472d38 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -173,7 +173,7 @@
         "ts-loader": "9.5.2",
         "tsconfig-paths-webpack-plugin": "4.2.0",
         "type-fest": "2.19.0",
-        "typescript": "5.5.4",
+        "typescript": "5.8.3",
         "typescript-eslint": "8.31.0",
         "typescript-strict-plugin": "2.4.4",
         "url": "0.11.4",
@@ -38542,9 +38542,10 @@
       }
     },
     "node_modules/typescript": {
-      "version": "5.5.4",
-      "resolved": "https://registry.npmjs.org/typescript/-/typescript-5.5.4.tgz",
-      "integrity": "sha512-Mtq29sKDAEYP7aljRgtPOpTvOfbwRWlS6dPRzwjdE+C0R4brX/GUyhHSecbHMFLNBLcJIPt9nl9yG5TZ1weH+Q==",
+      "version": "5.8.3",
+      "resolved": "https://registry.npmjs.org/typescript/-/typescript-5.8.3.tgz",
+      "integrity": "sha512-p1diW6TqL9L07nNxvRMM7hMMw4c5XOo/1ibL4aAIGmSAt9slTE1Xgw5KWuof2uTOvCg9BY7ZRi+GaF+7sfgPeQ==",
+      "dev": true,
       "license": "Apache-2.0",
       "bin": {
         "tsc": "bin/tsc",
diff --git a/package.json b/package.json
index 5015f8278b..97c6cc0eea 100644
--- a/package.json
+++ b/package.json
@@ -137,7 +137,7 @@
     "ts-loader": "9.5.2",
     "tsconfig-paths-webpack-plugin": "4.2.0",
     "type-fest": "2.19.0",
-    "typescript": "5.5.4",
+    "typescript": "5.8.3",
     "typescript-eslint": "8.31.0",
     "typescript-strict-plugin": "2.4.4",
     "url": "0.11.4",