topic Blue Prism 7.5.1 - 'Work Queues::Add to Queue' - 'Index was outside the bounds of the array.' in Upgrade Support

Blue Prism 7.5.1 - 'Work Queues::Add to Queue' - 'Index was outside the bounds of the array.'

stepher — Fri, 17 Apr 2026 18:48:58 GMT

Good afternoon, All,

I just started our initial investigation of Blue Prism v7.5.1. Right off the bat, I hit an issue. I figured I would start out here, assuming somebody would point me to something I am doing wrong, before I open a formal ticket.

I have a process that has been running more or less fine for the last several years (in versions 6.10.2 and 7.3.2). I just bundled everything up into a Release and imported it into our Sandbox and tried to run it...and no joy. When the process attempts to add an item to a Work Queue, the process hits an exception stating, 'Index was outside the bounds of the array.' Not sure which index, or which array.

MS Copilot seems to think it has to do with the Key field or Key Name. (It also said that the Tags field is a Collection... So, everything with a large grain of salt.) I have tried a few different things along this line, but no change in the exception.

Occam's Razor usually lands squarely on my shoulders, so I am expecting there is something I am, or am not doing.

Appreciate any advice,

Red

Re: Blue Prism 7.5.1 - 'Work Queues::Add to Queue' - 'Index was outside the bounds of the array.'

VanamalaSrinivas — Mon, 20 Apr 2026 12:38:13 GMT

Try verifying the item key number of characters is not greater than 255 as this is a limitation to the item key in Blue Prism that item key shouldn't exceed 255 characters.

Re: Blue Prism 7.5.1 - 'Work Queues::Add to Queue' - 'Index was outside the bounds of the array.'

stepher — Mon, 20 Apr 2026 14:21:01 GMT

@VanamalaSrinivas ,

Thanks for the response, but I am not sure this is it. The key field value that I am using is not very long. A sample value would be "12345678 | LIC1234567890", so maybe 20 - 25 characters in length, at the most.

I have tried variations of the 'pipe', changing it to an underscore, removing the spaces, just making it a strictly numeric value, and even leaving it blank. Nothing alters the error message at this point.

Thank you, though,

Red

Re: Blue Prism 7.5.1 - 'Work Queues::Add to Queue' - 'Index was outside the bounds of the array.'

stepher — Tue, 21 Apr 2026 20:55:43 GMT

Replying/Answering my own post feels somehow shady, but I wanted to close this topic out in case anyone else comes across it.

I did open a ticket with Support, and, after a couple of exchanges, we were able to confirm the source of the issue. It is actually a change in behavior in the 'Batch Size' parameter of the action in question. Historically, I have always set this to '0', which used to indicate that all records in your source collection would be loaded to the work queue en masse. That '0' is now causing the error. Setting it to a '1', or, presumably a higher value, allows the process to work as expected.

For myself, this is bothersome, but not much more, as I will need to sweep all instances of the 'Add to Queue' action to make this change. I load my work queue records one at a time, so settling on the '1' as the new standard is fine. Your mileage and/or perspective may vary.

Enjoy,

Red