Dynamics 365 V9.0: unable to decode the error log - dynamics-crm

Question

I am facing issue with all the plugins in the production as they all are failing with below log.
Unhandled exception:
Exception type: System.ServiceModel.FaultException`1[Microsoft.Xrm.Sdk.OrganizationServiceFault]
Message: Expected non-empty string.Detail:
<OrganizationServiceFault xmlns:i="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://schemas.microsoft.com/xrm/2011/Contracts">
<ActivityId>xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx</ActivityId>
<ErrorCode>-2147220989</ErrorCode>
<ErrorDetails xmlns:d2p1="http://schemas.datacontract.org/2004/07/System.Collections.Generic" />
<HelpLink></HelpLink>
<Message>Expected non-empty string.</Message>
<Timestamp>2019-07-29T12:36:40.3815746Z</Timestamp>
<ExceptionRetriable>false</ExceptionRetriable>
<ExceptionSource i:nil="true" />
<InnerFault>
<ActivityId>xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx</ActivityId>
<ErrorCode>-2147220970</ErrorCode>
<ErrorDetails xmlns:d3p1="http://schemas.datacontract.org/2004/07/System.Collections.Generic" />
<HelpLink i:nil="true" />
<Message>System.ArgumentException: Expected non-empty string.
Parameter name: settingName</Message>
<Timestamp>2019-07-29T12:36:40.3815746Z</Timestamp>
<ExceptionRetriable>false</ExceptionRetriable>
<ExceptionSource i:nil="true" />
<InnerFault i:nil="true" />
<OriginalException i:nil="true" />
<TraceText i:nil="true" />
</InnerFault>
<OriginalException i:nil="true" />
<TraceText i:nil="true" />
</OrganizationServiceFault>
As this is a limited message, I am not sure where to look.
Update 1: Earlier plugins were successfully executing, all of sudden it starts throwing exception. and I dont know where to find the field settingName, because this field is not there in any plugins or in any entity.
Update 2:
Entity List:
- Contact
- Appointment
- Task
- Phone Call
- CustomActivity
All the Plugins are registered for Post-Operation on either Create or Update Event

Answer 1

We had a priority ticket opened with Microsoft for this issue. We got the RCA from them saying as
Recent weekend deployment - Async machine went in invalid state and failing to deserialize the async context. They restarted the imapacted machine.