ArcGIS Pro 3.4 API Reference Guide
ArcGIS.Core.Data Namespace / Version Class / Post Method
If PostOptions.TargetVersion is not specified in postOptions, then the target version is the Default version.
Example Version

Post Method (Version)
Posts this version against a target version specified in postOptions. This method must be called on the MCT. Use QueuedTask.Run.
Syntax
public void Post( 
   PostOptions postOptions
)

Parameters

postOptions
If PostOptions.TargetVersion is not specified in postOptions, then the target version is the Default version.
Exceptions
ExceptionDescription
postOptions is null.
This operation is not supported in client-server mode because the data store supports multi-branch versioning.

A Selection object specified in PartialPostSelections is not from a feature service feature class.

-or-

Post cannot be performed in an active edit session.

A geodatabase-related exception has occurred.
This method or property must be called within the lambda passed to QueuedTask.Run
Remarks
If the underlying data store supports branch versioning and partial posting, this operation will post the data specified by PartialPostSelections to the Default version. In addition, after the partial posting operation is complete, the API will perform another Reconcile operation. This operation is not supported in traditional versioning.
Example
Reconciling and Posting a Version with its Parent in separate edit sessions
public void ReconcileAndPost(Geodatabase geodatabase)
{
    // Get a reference to our version and our parent
    if (geodatabase.IsVersioningSupported())
    {
        using (VersionManager versionManager = geodatabase.GetVersionManager())
        using (Version currentVersion = versionManager.GetCurrentVersion())
        using (Version parentVersion = currentVersion.GetParent())
        {

            //// Create a ReconcileDescription object
            //At 2.x - 
            //ReconcileDescription reconcileDescription = new ReconcileDescription(parentVersion);
            //reconcileDescription.ConflictResolutionMethod = ConflictResolutionMethod.Continue; // continue if conflicts are found
            //reconcileDescription.WithPost = true;

            //// Reconcile and post
            //ReconcileResult reconcileResult = currentVersion.Reconcile(reconcileDescription);

            // ReconcileResult.HasConflicts can be checked as-needed

            // Create a ReconcileOptions object
            ReconcileOptions reconcileOptions = new ReconcileOptions(parentVersion);
            reconcileOptions.ConflictResolutionMethod = ConflictResolutionMethod.Continue; // continue if conflicts are found
            reconcileOptions.ConflictDetectionType = ConflictDetectionType.ByRow; //Default
            reconcileOptions.ConflictResolutionType = ConflictResolutionType.FavorTargetVersion;//or FavorEditVersion

            // Reconcile
            ReconcileResult reconcileResult = currentVersion.Reconcile(reconcileOptions);
            if (!reconcileResult.HasConflicts)
            {
                //No conflicts, perform the post
                PostOptions postOptions = new PostOptions(parentVersion);
                //var postOptions = new PostOptions(); for default version
                postOptions.ServiceSynchronizationType = ServiceSynchronizationType.Synchronous;//Default
                currentVersion.Post(postOptions);
            }

        }
    }
}
Reconciling and Posting a Version with its Parent in the same edit session
public void ReconcileAndPost2(Geodatabase geodatabase)
{
    // Get a reference to our version and our parent
    if (geodatabase.IsVersioningSupported())
    {
        using (VersionManager versionManager = geodatabase.GetVersionManager())
        using (Version currentVersion = versionManager.GetCurrentVersion())
        using (Version parentVersion = currentVersion.GetParent())
        {

            //// Create a ReconcileDescription object
            //At 2.x - 
            //ReconcileDescription reconcileDescription = new ReconcileDescription(parentVersion);
            //reconcileDescription.ConflictResolutionMethod = ConflictResolutionMethod.Continue; // continue if conflicts are found
            //reconcileDescription.WithPost = true;

            //// Reconcile and post
            //ReconcileResult reconcileResult = currentVersion.Reconcile(reconcileDescription);

            // ReconcileResult.HasConflicts can be checked as-needed

            // Create a ReconcileOptions object
            ReconcileOptions reconcileOptions = new ReconcileOptions(parentVersion);
            reconcileOptions.ConflictResolutionMethod = ConflictResolutionMethod.Continue; // continue if conflicts are found
            reconcileOptions.ConflictDetectionType = ConflictDetectionType.ByRow; //Default
            reconcileOptions.ConflictResolutionType = ConflictResolutionType.FavorTargetVersion;//or FavorEditVersion

            PostOptions postOptions = new PostOptions(parentVersion);
            //var postOptions = new PostOptions(); for default version
            postOptions.ServiceSynchronizationType = ServiceSynchronizationType.Synchronous;//Default

            // Reconcile
            ReconcileResult reconcileResult = currentVersion.Reconcile(reconcileOptions, postOptions);
            if (reconcileResult.HasConflicts)
            {
                //TODO resolve conflicts

            }

        }
    }
}
Requirements

Target Platforms: Windows 11, Windows 10

ArcGIS Pro version: 3 or higher.
See Also