"Invalid parameter ‘formid=xxxxxxxx-xxxx-xxxxx-′ in Request.QueryString on page .../workplace/home_dashboards.aspx"
The main thing I noticed about the error message was that the guid in the parameter was being truncated, this meant that the guid was incomplete that was used in the query string. There had been no changes to the system recently and it seemed to start happening without any warning.
I had never seen this particular one before, but we were able to resolve it and even find out how to prevent it in the future. Some searching revealed that other people have had this problem before and that the parameter that causes the problem is not always the same. In the example given here it seemed that the OTC (Object Type Code) was being truncated in the same fashion.
The fix for this issue was ultimately performing an IIS Reset. This quickly resolved the problem for the client. Some further searching seemed to suggest that staying current on your update rollups may prevent this from happening to you because there has been fixes implemented for issues of this type in both Rollup 5 and Rollup 7.
I hope this helps.