Getting Lists causes 'Instance Was deleted Error'

In my solution I’m trying to read all SharePoint Online data of a tenant, and in order to improve performance and reduce the amount of objects in memory, I use separate threads for each SharePoint object. The PnPContext is created only once per URL, stored in a Map and re-used as needed.

When I try to read Lists from Web I sometimes get the following exception:

This model instance was deleted, you can't use it anymore

at PnP.Core.Model.TransientObject.CheckDeleted()
at PnP.Core.Model.TransientObject.GetValue[T](String propertyName)
at PnP.Core.Model.BaseDataModel`1.GetModelCollectionValue[T](String propertyName)
at PnP.Core.Model.SharePoint.Web.get_Lists()

Code I use for loading Lists:

var list = context.Web.Lists.GetById(new Guid("xxxxx")

Important: I have multiple threads running parallel that are probably using the same Context to load different Lists of the current Web.

[KoenZomers]

Ran into the same here with only two concurrent threads. Cloning the PnPContext for every call as Bert mentions above fixed it for me.

[jansenbe]

@bajce : if you want to run work for the same IWeb in parallel via threads then cloning a context should fix things for you. https://pnp.github.io/pnpcore/using-the-sdk/basics-context.html#cloning-a-pnpcontext-for-the-same-web describes the details, but a default clone operation will not result in a server roundtrip. If you however optimized the initial load as described in my previous reply, then not all properties are copied over to the cloned context.

If this answers your questions, then please close the issue.