MT5 Build 5505 – Optimization fails on Custom Symbols - ticks send error / history synchronization interrupted

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Hello

I am experiencing a problem in MT5 Build 5505 after the update on 16 Jan 2026. The issue occurs **only with optimization of EAs on custom symbols**. Here are the details:

1. **MT5 Build:** 5505  
2. **Problem:** Optimization stops with errors:  
   - "ticks send error"  
   - "ticks synchronization interrupted"  
3. **Symbols affected:** Only Custom Symbols (EURUSD, USDJPY, others created as custom)  
4. **Tick data:** Downloaded and imported correctly  
5. **EAs tested:** Multiple EAs (all work fine on regular symbols)  
6. **Agents:** Multi-agent optimization tested  
7. **Steps already tried:**  
   - Reinstalled MT5  
   - Cleared cache  
   - Used only one agent  
   - Forward testing  
8. **Previous behavior:** Worked perfectly on builds before 16 Jan 2026  

Is this a known bug in Build 5505 affecting custom symbols optimization? Is there a workaround, or will it be fixed in an upcoming update?

 
Ahmed Sabba:
The issue occurs **only with optimization of EAs on custom symbols...

You'd have to post your EA code to get a 100% accurate answer.

Having said that, the general cause of your opening statement is failing to specify a separate tradable symbol (order handling) in the EA code where the EA is running on a custom symbol. 

 
Ryan L Johnson #:
You'd have to post your EA code to get a 100% accurate answer.

What is needed is a way to reproduce it, not necessarily their advisor code. If it can be reproduced using MT5's built-in EA, great.

I don't have enough experience to try to reproduce this. Let's wait for someone more qualified in this matter...

 
Ahmed Sabba:
Hello

I am experiencing a problem in MT5 Build 5505 after the update on 16 Jan 2026. The issue occurs **only with optimization of EAs on custom symbols**. Here are the details:

1. **MT5 Build:** 5505  
2. **Problem:** Optimization stops with errors:  
   - "ticks send error"  
   - "ticks synchronization interrupted"  
3. **Symbols affected:** Only Custom Symbols (EURUSD, USDJPY, others created as custom)  
4. **Tick data:** Downloaded and imported correctly  
5. **EAs tested:** Multiple EAs (all work fine on regular symbols)  
6. **Agents:** Multi-agent optimization tested  
7. **Steps already tried:**  
   - Reinstalled MT5  
   - Cleared cache  
   - Used only one agent  
   - Forward testing  
8. **Previous behavior:** Worked perfectly on builds before 16 Jan 2026  

Is this a known bug in Build 5505 affecting custom symbols optimization? Is there a workaround, or will it be fixed in an upcoming update?

Please provide the full log file, not screenshots. 
 
Alain Verleyen #:
Please provide the full log file, not screenshots. 

Here is the log file

Files:
20260117.log  23 kb
 
Ryan L Johnson #:

You'd have to post your EA code to get a 100% accurate answer.

Having said that, the general cause of your opening statement is failing to specify a separate tradable symbol (order handling) in the EA code where the EA is running on a custom symbol. 

 I know very well when an EA has a problem and when the terminal itself is causing it. This issue is clearly on MT5 Build 5505, not the EA.

Thanks!


 
Ahmed Sabba #:

Here is the log file

Thanks. I will check and get back to you.
 
Alain Verleyen #:
Thanks. I will check and get back to you.
ok thank you
 
I have tested this build https://t.me/MT5Exe/6 that you uploaded earlier. Everything is working perfectly, except for an error occurring in build 5505.
MT5 release exe files
  • t.me
MT5 Build 5430 AVX2 exe files.
 

This issue is a general issue on the Strategy Tester with recent beta 5505/5506, not related specifically to Custom symbols.

Confirmed and reported to MQ attention.

In the meantime you can downgrade to build 5430.

Forum on trading, automated trading systems and testing trading strategies

All about MT5 updates.

Alain Verleyen, 2025.12.16 22:54

In case you got an BETA update, for whatever reason, and you want to move to the last official release :

  • A Telegram channel has been created, you will always find there the last official release needed exe files.
  • MT5 Terminal is available in several versions according to your CPU capabilities. You can check which version you have to use in the Journal log, at the first entries after you started MT5.

Here my version is AVX2, an other possibility is X64

  • With this information you will know which zip file to download.


  • You then just have to replace your current exe files with the ones from the Zip. If you don't know how to do, then doing this operation is probably not a good idea.

After MT5 is restarted, you will have the last official release.

If you don't want to get beta-build updates again :

  • NEVER connect to MetaQuotes-Demo server.
  • NEVER use MT5 Terminal Help menu=>Check for Updates=>Last Beta Version.

 
Alain Verleyen #:

This issue is a general issue on the Strategy Tester with recent beta 5505/5506, not related specifically to Custom symbols.

Confirmed and reported to MQ attention.

In the meantime you can downgrade to build 5430.

I successfully downgraded to build 5430 and everything is working perfectly now.
Thank you so much for the help and confirmation, I really appreciate it.
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