diff --git a/app/cabinet/routes/auth.py b/app/cabinet/routes/auth.py
index c0635039..db84eb1d 100644
--- a/app/cabinet/routes/auth.py
+++ b/app/cabinet/routes/auth.py
@@ -7,6 +7,7 @@ from datetime import UTC, datetime
 
 from fastapi import APIRouter, Depends, HTTPException, status
 from sqlalchemy import select
+from sqlalchemy.exc import IntegrityError
 from sqlalchemy.ext.asyncio import AsyncSession
 
 from app.config import settings
@@ -1010,7 +1011,14 @@ async def request_email_change(
         user.email_verification_token = verification_token
         user.email_verification_expires = verification_expires
 
-        await db.commit()
+        try:
+            await db.commit()
+        except IntegrityError:
+            await db.rollback()
+            raise HTTPException(
+                status_code=status.HTTP_400_BAD_REQUEST,
+                detail='This email is already registered',
+            )
 
         if settings.is_cabinet_email_verification_enabled() and email_service.is_configured():
             cabinet_url = settings.CABINET_URL
@@ -1031,16 +1039,19 @@ async def request_email_change(
             )
             custom_subject, custom_body = override if override else (None, None)
 
-            await asyncio.to_thread(
-                email_service.send_verification_email,
-                to_email=request.new_email,
-                verification_token=verification_token,
-                verification_url=verification_url,
-                username=user.first_name,
-                language=lang,
-                custom_subject=custom_subject,
-                custom_body_html=custom_body,
-            )
+            try:
+                await asyncio.to_thread(
+                    email_service.send_verification_email,
+                    to_email=request.new_email,
+                    verification_token=verification_token,
+                    verification_url=verification_url,
+                    username=user.first_name,
+                    language=lang,
+                    custom_subject=custom_subject,
+                    custom_body_html=custom_body,
+                )
+            except Exception as e:
+                logger.error(f'Failed to send verification email to {request.new_email} for user {user.id}: {e}')
 
         logger.info(f'Unverified email replaced for user {user.id}: {old_email} -> {request.new_email}')
 
diff --git a/app/config.py b/app/config.py
index 651548cc..e81dcb7c 100644
--- a/app/config.py
+++ b/app/config.py
@@ -1057,7 +1057,7 @@ class Settings(BaseSettings):
         if not sanitized_username:
             sanitized_username = f'user_{identifier}'
 
-        return sanitized_username[:64]
+        return sanitized_username[:36]
 
     @staticmethod
     def parse_daily_time_list(raw_value: str | None) -> list[time]:
diff --git a/app/handlers/start.py b/app/handlers/start.py
index d4b9e829..21e56260 100644
--- a/app/handlers/start.py
+++ b/app/handlers/start.py
@@ -1225,6 +1225,20 @@ async def complete_registration_from_callback(callback: types.CallbackQuery, sta
             )
             logger.info(f'✅ Приветственное сообщение отправлено пользователю {user.telegram_id}')
             await _send_pinned_message(callback.bot, db, user)
+        except TelegramBadRequest as e:
+            if 'parse entities' in str(e).lower() or "can't parse" in str(e).lower():
+                logger.warning(f'HTML parse error в приветственном сообщении, повтор без parse_mode: {e}')
+                try:
+                    await callback.message.answer(
+                        offer_text,
+                        reply_markup=get_post_registration_keyboard(user.language),
+                        parse_mode=None,
+                    )
+                    await _send_pinned_message(callback.bot, db, user)
+                except Exception as fallback_err:
+                    logger.error(f'Ошибка при повторной отправке приветственного сообщения: {fallback_err}')
+            else:
+                logger.error(f'Ошибка при отправке приветственного сообщения: {e}')
         except Exception as e:
             logger.error(f'Ошибка при отправке приветственного сообщения: {e}')
     else:
@@ -1504,6 +1518,20 @@ async def complete_registration(message: types.Message, state: FSMContext, db: A
             )
             logger.info(f'✅ Приветственное сообщение отправлено пользователю {user.telegram_id}')
             await _send_pinned_message(message.bot, db, user)
+        except TelegramBadRequest as e:
+            if 'parse entities' in str(e).lower() or "can't parse" in str(e).lower():
+                logger.warning(f'HTML parse error в приветственном сообщении, повтор без parse_mode: {e}')
+                try:
+                    await message.answer(
+                        offer_text,
+                        reply_markup=keyboard,
+                        parse_mode=None,
+                    )
+                    await _send_pinned_message(message.bot, db, user)
+                except Exception as fallback_err:
+                    logger.error(f'Ошибка при повторной отправке приветственного сообщения: {fallback_err}')
+            else:
+                logger.error(f'Ошибка при отправке приветственного сообщения: {e}')
         except Exception as e:
             logger.error(f'Ошибка при отправке приветственного сообщения: {e}')
     else: