Why did this happen?

The main reason for this error on your MetaTrader platform is that a trade is being made for a volume beyond the limits set by the broker. Here are a few instances why this may happen:

• Exness has certain limits on the volume of each trade placed in certain instruments based on the trading account type and the time of the day when the trade is placed. 
• Your Expert Advisor (EA) may be attempting to open a trade for a volume that is beyond the limits set for that particular instrument or that account type.
• You may have manually set up a pending order for a trade for a volume that doesn’t meet the limitations at the time when it is ready for execution. For example, trade for 100 lots in a certain instrument, which hits the expected price during night-time when the only permissible quantity per trade is 60 lots.

How to solve this error?

To avoid this, make sure you place your trades well within the limits Exness sets and ensure your EA settings are done accordingly. Limits can be checked for each instrument under its own contract specifications in the terminal.

If the issue persists, open a ticket in the support hub for assistance.