diff --git a/src/main/webapp/resources/js/apis/export/ncbi.ts b/src/main/webapp/resources/js/apis/export/ncbi.ts
index 9719af86548..5ba6fdf4774 100644
--- a/src/main/webapp/resources/js/apis/export/ncbi.ts
+++ b/src/main/webapp/resources/js/apis/export/ncbi.ts
@@ -96,5 +96,8 @@ export async function getNCBISelections(): Promise<NcbiSelection[]> {
 export async function submitNcbiSubmissionRequest(
   request: NcbiSubmissionRequest
 ) {
-  return await post(setBaseUrl(`ajax/ncbi/submit`), request);
+  return await post<void, NcbiSubmissionRequest>(
+    setBaseUrl(`ajax/ncbi/submit`),
+    request
+  );
 }
diff --git a/src/main/webapp/resources/js/apis/projects/samples.ts b/src/main/webapp/resources/js/apis/projects/samples.ts
index 12792fcf2c5..3f67533d268 100644
--- a/src/main/webapp/resources/js/apis/projects/samples.ts
+++ b/src/main/webapp/resources/js/apis/projects/samples.ts
@@ -3,6 +3,10 @@ import {
   PairedEndSequenceFile,
   SingleEndSequenceFile,
 } from "../../types/irida";
+import {
+  AjaxErrorResponse,
+  AjaxSuccessResponse,
+} from "../../types/ajax-response";
 import { getProjectIdFromUrl, setBaseUrl } from "../../utilities/url-utilities";
 import { get, post } from "../requests";
 
@@ -123,14 +127,17 @@ export async function shareSamplesWithProject({
   targetId: number;
   locked: boolean;
   remove: boolean;
-}) {
-  return post(setBaseUrl(`ajax/samples/share`), {
-    currentId,
-    sampleIds,
-    targetId,
-    locked,
-    remove,
-  });
+}): Promise<AjaxErrorResponse | AjaxSuccessResponse> {
+  return post<AjaxErrorResponse | AjaxSuccessResponse>(
+    setBaseUrl(`ajax/samples/share`),
+    {
+      currentId,
+      sampleIds,
+      targetId,
+      locked,
+      remove,
+    }
+  );
 }
 
 /**
diff --git a/src/main/webapp/resources/js/apis/requests.ts b/src/main/webapp/resources/js/apis/requests.ts
index 7a5ba6ee72b..fc90b098496 100644
--- a/src/main/webapp/resources/js/apis/requests.ts
+++ b/src/main/webapp/resources/js/apis/requests.ts
@@ -20,11 +20,10 @@ export async function get<T>(
   }
 }
 
-export async function post<T>(
-  url: string,
-  params?: T,
-  config?: AxiosRequestConfig
-): Promise<T> {
+export async function post<
+  T,
+  P = FormData | Record<string, unknown> | undefined
+>(url: string, params?: P, config?: AxiosRequestConfig): Promise<T> {
   try {
     const { data } = await axios.post(url, params, config);
     return data;
@@ -36,7 +35,14 @@ export async function post<T>(
         return Promise.reject(error.message);
       }
     } else if (axios.isCancel(error)) {
-      return Promise.reject(error.message);
+      let message;
+      if (error instanceof Error) {
+        const { message: destructuredMessage } = error;
+        message = destructuredMessage;
+      } else {
+        message = String(error);
+      }
+      return Promise.reject(message);
     } else {
       return Promise.reject("An unexpected error occurred");
     }
diff --git a/src/main/webapp/resources/js/apis/samples/samples.ts b/src/main/webapp/resources/js/apis/samples/samples.ts
index c2e81867ab4..f08d01eb8f6 100644
--- a/src/main/webapp/resources/js/apis/samples/samples.ts
+++ b/src/main/webapp/resources/js/apis/samples/samples.ts
@@ -394,10 +394,14 @@ export const uploadSequenceFiles = async ({
   config,
 }: {
   sampleId: number;
-  formData: any;
+  formData: FormData;
   config: Record<string, unknown>;
 }): Promise<SampleSequencingObject[]> => {
-  return post(`${URL}/${sampleId}/sequenceFiles/upload`, formData, config);
+  return post<SampleSequencingObject[], FormData>(
+    `${URL}/${sampleId}/sequenceFiles/upload`,
+    formData,
+    config
+  );
 };
 
 /**
@@ -413,10 +417,14 @@ export const uploadAssemblyFiles = ({
   config,
 }: {
   sampleId: number;
-  formData: any;
+  formData: FormData;
   config: Record<string, unknown>;
 }): Promise<SampleGenomeAssembly[]> => {
-  return post(`${URL}/${sampleId}/assemblies/upload`, formData, config);
+  return post<SampleGenomeAssembly[], FormData>(
+    `${URL}/${sampleId}/assemblies/upload`,
+    formData,
+    config
+  );
 };
 
 /**
@@ -432,8 +440,12 @@ export const uploadFast5Files = ({
   config,
 }: {
   sampleId: number;
-  formData: any;
+  formData: FormData;
   config: Record<string, unknown>;
 }): Promise<SampleSequencingObject[]> => {
-  return post(`${URL}/${sampleId}/fast5/upload`, formData, config);
+  return post<SampleSequencingObject[], FormData>(
+    `${URL}/${sampleId}/fast5/upload`,
+    formData,
+    config
+  );
 };
diff --git a/src/main/webapp/resources/js/types/ajax-response.d.ts b/src/main/webapp/resources/js/types/ajax-response.d.ts
index 08a4051aaa5..a1c8c2881a4 100644
--- a/src/main/webapp/resources/js/types/ajax-response.d.ts
+++ b/src/main/webapp/resources/js/types/ajax-response.d.ts
@@ -1,7 +1,12 @@
-interface AjaxErrorResponse {
-  error: string;
-}
+export = AJAXRESPONSE;
+export as namespace AJAXRESPONSE;
+
+declare namespace AJAXRESPONSE {
+  export type AjaxErrorResponse = {
+    error: string;
+  };
 
-interface AjaxSuccessResponse {
-  message: string;
+  export type AjaxSuccessResponse = {
+    message: string;
+  };
 }