diff --git a/src/lib/download-request.ts b/src/lib/download-request.ts
index c3b94fa..43d14a0 100644
--- a/src/lib/download-request.ts
+++ b/src/lib/download-request.ts
@@ -67,7 +67,7 @@ export class DownloadRequest extends TypedEventTarget<
 					this.#updateState({ status: 'canceled' })
 				} else if (getErrorCode(error)) {
 					// Specific known error from the server
-					this.#updateState({ status: 'error', error })
+					this.#updateState({ status: 'error', error: jsonError(error) })
 				} else {
 					// Once the download has started, the sender can only close the
 					// connection to cancel the download, which we only see as an
diff --git a/src/lib/map-share.ts b/src/lib/map-share.ts
index a795dc9..2178706 100644
--- a/src/lib/map-share.ts
+++ b/src/lib/map-share.ts
@@ -5,7 +5,7 @@ import {
 	type DownloadStateUpdate,
 	type MapInfo,
 } from '../types.js'
-import { errors } from './errors.js'
+import { errors, jsonError } from './errors.js'
 import { StateUpdateEvent } from './state-update-event.js'
 import { addTrailingSlash, generateId, getErrorCode } from './utils.js'
 
@@ -155,7 +155,7 @@ export class DownloadResponse extends TypedEventTarget<
 				} else if (getErrorCode(error) === 'ECONNRESET') {
 					this.#updateState({ status: 'aborted' })
 				} else {
-					this.#updateState({ status: 'error', error })
+					this.#updateState({ status: 'error', error: jsonError(error) })
 				}
 			})
 
diff --git a/test/map-shares.test.ts b/test/map-shares.test.ts
index 3c81d6a..e218e81 100644
--- a/test/map-shares.test.ts
+++ b/test/map-shares.test.ts
@@ -361,6 +361,7 @@ describe('Map Shares and Downloads', () => {
 				'error.code',
 				'DOWNLOAD_SHARE_NOT_PENDING',
 			)
+			expect(events.at(-1)).toHaveProperty('error.message')
 
 			await completedPromise
 		}, 2000)
@@ -385,6 +386,7 @@ describe('Map Shares and Downloads', () => {
 				'error.code',
 				'DOWNLOAD_SHARE_NOT_PENDING',
 			)
+			expect(events.at(-1)).toHaveProperty('error.message')
 		})
 	})
 
@@ -582,6 +584,7 @@ describe('Map Shares and Downloads', () => {
 					'error.code',
 					'DOWNLOAD_SHARE_DECLINED',
 				)
+				expect(events.at(-1)).toHaveProperty('error.message')
 			})
 
 			it('should reject decline on non-pending share', async (t) => {
@@ -1590,6 +1593,7 @@ describe('Map Shares and Downloads', () => {
 				.json<any>()
 			expect(downloadStatus.status).toBe('error')
 			expect(downloadStatus).toHaveProperty('error.code', 'DOWNLOAD_ERROR')
+			expect(downloadStatus).toHaveProperty('error.message')
 		})
 
 		it('should clean up temp files on download error', async (t) => {