We are running into an issue using a custom file manager that we have. when trying to upload a file we receive this error: A critical error has occurred. This happens when a user (whether it's a normal user, administrator, or host account) tries to upload any file type.

 AssemblyVersion: 5.3.0
PortalID: 0
PortalName: My Website
UserID: 1
UserName: host
ActiveTabID: 63
ActiveTabName: CM File Manager
RawURL: /CMAdmin/CMFileManager/tabid/63/ctl/Upload/mid/386/ftype/File/rtab/63/Default.aspx
AbsoluteURL: /Default.aspx
AbsoluteURLReferrer: http://website.com/CMAdmin/CMFileManager/tabid/63/ctl/Upload/mid/386/ftype/File/rtab/63/Default.aspx
UserAgent: Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US) AppleWebKit/532.5 (KHTML, like Gecko) Chrome/4.1.249.1036 Safari/532.5
DefaultDataProvider: DotNetNuke.Data.SqlDataProvider, DotNetNuke.SqlDataProvider
ExceptionGUID: 9f6152ff-3690-433e-a7be-05d6ac76a425
InnerException: Could not load type 'DotNetNuke.Services.Localization.LocaleFilePackReader' from assembly 'DotNetNuke, Version=5.3.0.205, Culture=neutral, PublicKeyToken=null'.
FileName: 
FileLineNumber: 0
FileColumnNumber: 0
Method: Netlab.dnn.modules.FileManager.WebUpload.cmdUpload_Click
StackTrace: 
Message: DotNetNuke.Services.Exceptions.PageLoadException: Could not load type 'DotNetNuke.Services.Localization.LocaleFilePackReader' from assembly 'DotNetNuke, Version=5.3.0.205, Culture=neutral, PublicKeyToken=null'. ---> System.TypeLoadException: Could not load type 'DotNetNuke.Services.Localization.LocaleFilePackReader' from assembly 'DotNetNuke, Version=5.3.0.205, Culture=neutral, PublicKeyToken=null'. at Netlab.dnn.modules.FileManager.WebUpload.cmdUpload_Click(Object sender, EventArgs e) at System.Web.UI.WebControls.LinkButton.OnClick(EventArgs e) at System.Web.UI.WebControls.LinkButton.RaisePostBackEvent(String eventArgument) at System.Web.UI.WebControls.LinkButton.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(String eventArgument) at System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument) at System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData) at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) --- End of inner exception stack trace ---
Source: 
Server Name: server

NOTE: this is happening in 5.2.3 and 5.3.0... i accidentally pasted the error from the 5.3.0 test install. same error in both versions, just different version numbers in the error

It is the same error in DNN 5.2.3. i accidentally pasted the error from the 5.3.0 test install instead of the 5.2.3 install (too many tabs open!). same error in both versions, just different version numbers in the error