Who is this article for?

Users who encounter the listed error messages

When a screen loads or updates, the application makes a number of request to the server.  Sometimes it is possible to click on an area of the screen that is awaiting information, and an error will occur.  This article describes the symptoms and how to work round the problem.

1. Symptoms
2. Working round async problems

1. Symptoms

Sometimes it is possible to click on a button that performs a function while it is awaiting data from from the server.

In these cases an error will appear on screen.  Messages are:

Collection was modified; enumeration operation may not execute.

An exception occurred during the operation, making the result invalid.
Check InnerException for exception details.

Index must be within the bounds of the List

Such errors may be resolved in later versions of the application. 

2. Working round async issues

If you find that such errors appear in your system:

• Please get in touch with the support team, who can advise whether you are experiencing a known issue
• As the issue occurs while the application is waiting for data, you can minimise the chances of experiencing an error message by allowing some additional time before clicking the affected button / grid
• Also consider closing the Property Grid if you don’t need it (as this is one less thing to keep refreshed)