Lỗi web khi upload lên hosting trong asp.net lúc bị lúc không

Hi mọi người, mình gặp vấn đề khá khó khăn, không biết giải quyết làm sao. Web mình chạy local khá OK, nhưng khi upload lên hosting, lúc chạy phần quản trị dữ liệu, phần admin, thêm xóa sửa sản phẩm thường bị lỗi như dưới.

Lỗi này lúc bị lúc không, lúc đang lưu dữ liệu thì bị, khá bực bội.

Trước kia mình xài OK không sao, tự dung dạo này nó bị hoài, mình nhờ hosting thì họ nói báo về bên lập trình web, bên lập trình thì họ nói lỗi do hosting hizzz, mình không biết làm ntn, đầu tư cái web mà bị lỗi bực quá (

Giuppppppppppppp với mọi người ơi. mình cũng biết chút về code, nên chỉ mình cách với

Lỗi: Validation of viewstate MAC failed. If this application is hosted by a Web Farm or cluster, ensure that <machineKey> configuration specifies the same validationKey and validation algorithm. AutoGenerate cannot be used in a cluster

Mã:

Server Error in '/' Application.
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Validation of viewstate MAC failed. If this application is hosted by a Web Farm or cluster, ensure that <machineKey> configuration specifies the same validationKey and validation algorithm. AutoGenerate cannot be used in a cluster.

See http://go.microsoft.com/fwlink/?LinkID=314055 for more information.
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.Web.HttpException: Validation of viewstate MAC failed. If this application is hosted by a Web Farm or cluster, ensure that <machineKey> configuration specifies the same validationKey and validation algorithm. AutoGenerate cannot be used in a cluster.

See http://go.microsoft.com/fwlink/?LinkID=314055 for more information.

Source Error:

[No relevant source lines]

Source File: c:\windows\Microsoft.NET\Framework\v4.0.30319\Temporary ASP.NET Files\root\96c4b5e9\43b13487\App_Web_fywircax.0.cs    Line: 0

Stack Trace:

[ViewStateException: Invalid viewstate.
    Client IP: 171.232.175.242
    Port: 62623
    Referer: http://xxxx.com.vn/fx/sialand.aspx
    Path: /Admincp/webconfig.aspx
    User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:49.0) Gecko/20100101 Firefox/49.0
    ViewState: 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...]

[HttpException (0x80004005): Validation of viewstate MAC failed. If this application is hosted by a Web Farm or cluster, ensure that <machineKey> configuration specifies the same validationKey and validation algorithm. AutoGenerate cannot be used in a cluster.

See http://go.microsoft.com/fwlink/?LinkID=314055 for more information.]
   System.Web.UI.ViewStateException.ThrowError(Exception inner, String persistedState, String errorPageMessage, Boolean macValidationError) +116
   System.Web.UI.ObjectStateFormatter.Deserialize(String inputString, Purpose purpose) +425
   System.Web.UI.ObjectStateFormatter.System.Web.UI.IStateFormatter2.Deserialize(String serializedState, Purpose purpose) +13
   System.Web.UI.Util.DeserializeWithAssert(IStateFormatter2 formatter, String serializedState, Purpose purpose) +40
   System.Web.UI.HiddenFieldPageStatePersister.Load() +247
   System.Web.UI.Page.LoadPageStateFromPersistenceMedium() +251
   System.Web.UI.Page.LoadAllState() +41
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +6211
   System.Web.UI.Page.ProcessRequest(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +245
   System.Web.UI.Page.ProcessRequest() +72
   System.Web.UI.Page.ProcessRequestWithNoAssert(HttpContext context) +22
   System.Web.UI.Page.ProcessRequest(HttpContext context) +58
   ASP.admincp_waddnewproducts_aspx.ProcessRequest(HttpContext context) in c:\windows\Microsoft.NET\Framework\v4.0.30319\Temporary ASP.NET Files\root\96c4b5e9\43b13487\App_Web_fywircax.0.cs:0
   System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +188
   System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +69


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Version Information: Microsoft .NET Framework Version:4.0.30319; ASP.NET Version:4.6.1069.1