diff --git a/keyserver/src/updaters/thread-updaters.js b/keyserver/src/updaters/thread-updaters.js
--- a/keyserver/src/updaters/thread-updaters.js
+++ b/keyserver/src/updaters/thread-updaters.js
@@ -6,6 +6,7 @@
   roleIsAdminRole,
   viewerIsMember,
   getThreadTypeParentRequirement,
+  validChatNameRegex,
 } from 'lib/shared/thread-utils.js';
 import { hasMinCodeVersion } from 'lib/shared/version-utils.js';
 import type { Shape } from 'lib/types/core.js';
@@ -333,6 +334,9 @@
   const untrimmedName = request.changes.name;
   if (untrimmedName !== undefined && untrimmedName !== null) {
     const name = firstLine(untrimmedName);
+    if (name.search(validChatNameRegex) === -1) {
+      throw new ServerError('invalid_chat_name');
+    }
     changedFields.name = name;
     sqlUpdate.name = name ?? null;
   }
diff --git a/lib/shared/thread-utils.js b/lib/shared/thread-utils.js
--- a/lib/shared/thread-utils.js
+++ b/lib/shared/thread-utils.js
@@ -90,6 +90,12 @@
 import { firstLine } from '../utils/string-utils.js';
 import { trimText } from '../utils/text-utils.js';
 
+const chatNameMaxLength = 191;
+const chatNameMinLength = 0;
+const secondCharRange = `{${chatNameMinLength},${chatNameMaxLength}}`;
+const validChatNameRegexString = `^.${secondCharRange}$`;
+const validChatNameRegex: RegExp = new RegExp(validChatNameRegexString);
+
 function colorIsDark(color: string): boolean {
   return tinycolor(`#${color}`).isDark();
 }
@@ -1530,4 +1536,6 @@
   getAvailableThreadMemberActions,
   selectedThreadColors,
   threadMembersWithoutAddedAshoat,
+  validChatNameRegex,
+  chatNameMaxLength,
 };
diff --git a/native/chat/settings/thread-settings-name.react.js b/native/chat/settings/thread-settings-name.react.js
--- a/native/chat/settings/thread-settings-name.react.js
+++ b/native/chat/settings/thread-settings-name.react.js
@@ -15,6 +15,7 @@
   changeThreadSettings,
 } from 'lib/actions/thread-actions.js';
 import { createLoadingStatusSelector } from 'lib/selectors/loading-selectors.js';
+import { chatNameMaxLength } from 'lib/shared/thread-utils.js';
 import type { LoadingStatus } from 'lib/types/loading-types.js';
 import {
   type ResolvedThreadInfo,
@@ -108,6 +109,7 @@
           editable={this.props.loadingStatus !== 'loading'}
           ref={this.textInputRef}
           selectionColor={`#${this.props.threadInfo.color}`}
+          maxLength={chatNameMaxLength}
         />
         {button}
       </React.Fragment>
diff --git a/web/modals/input.react.js b/web/modals/input.react.js
--- a/web/modals/input.react.js
+++ b/web/modals/input.react.js
@@ -19,6 +19,7 @@
   ...BaseInputProps,
   +type: string,
   +placeholder: string,
+  +maxLength?: number,
 };
 
 function Input(props: InputProps, ref): React.Node {
diff --git a/web/modals/threads/settings/thread-settings-general-tab.react.js b/web/modals/threads/settings/thread-settings-general-tab.react.js
--- a/web/modals/threads/settings/thread-settings-general-tab.react.js
+++ b/web/modals/threads/settings/thread-settings-general-tab.react.js
@@ -7,7 +7,10 @@
   changeThreadSettingsActionTypes,
   changeThreadSettings,
 } from 'lib/actions/thread-actions.js';
-import { threadHasPermission } from 'lib/shared/thread-utils.js';
+import {
+  threadHasPermission,
+  chatNameMaxLength,
+} from 'lib/shared/thread-utils.js';
 import { type SetState } from 'lib/types/hook-types.js';
 import {
   type ThreadInfo,
@@ -153,6 +156,7 @@
         <div className={css.form_content}>
           <Input
             type="text"
+            maxLength={chatNameMaxLength}
             value={firstLine(queuedChanges.name ?? threadInfo.name)}
             placeholder={threadNamePlaceholder}
             onChange={onChangeName}