[Full-disclosure] I was browsing the web and noticed this, anyone have an idea?

[d e f c o n]

I am getting an error on my website when I input `--1--` as login and
password, how do I patch this and what does this mean?  Could I get hacked?
Or is this nothing to worrie about?
defcon
Offending URL: https://somewebsite.com
Source: System.Web

Message: Input string was not in a correct format.

Stack trace: at System.Web.UI.Page.HandleError(Exception e) at
System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint,
Boolean includeStagesAfterAsyncPoint) at
System.Web.UI.Page.ProcessRequest(Boolean
includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) at
System.Web.UI.Page.ProcessRequest() at
System.Web.UI.Page.ProcessRequestWithNoAssert(HttpContext context) at
System.Web.UI.Page.ProcessRequest(HttpContext context) at
ASP.loginpage_aspx.ProcessRequest(HttpContext context) at
System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean&
completedSynchronously)
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