I am facing the following issue.could anyone give step by step fix for this

Strict Standards: Declaration of DataObjectManager::FieldHolder() should be compatible with that of ComplexTableField::FieldHolder() in /home/content/31/9840731/html/event/dataobject_manager/code/DataObjectManager.php on line 4

Strict Standards: Declaration of DataObjectManager_Item::Link() should be compatible with that of ComplexTableField_Item::Link() in /home/content/31/9840731/html/event/dataobject_manager/code/DataObjectManager.php on line 644

Strict Standards: Declaration of DataObjectManager_Item::Fields() should be compatible with that of TableListField_Item::Fields() in /home/content/31/9840731/html/event/dataobject_manager/code/DataObjectManager.php on line 644

Strict Standards: Declaration of DataObjectManager_ItemRequest::Link() should be compatible with that of ComplexTableField_ItemRequest::Link() in /home/content/31/9840731/html/event/dataobject_manager/code/DataObjectManager.php on line 916

Strict Standards: Declaration of AssetManagerFolder::updateCMSFields() should be compatible with that of DataExtension::updateCMSFields() in /home/content/31/9840731/html/event/dataobject_manager/code/AssetManagerFolder.php on line 4

Strict Standards: Declaration of SortableDataObject::extraStatics() should be compatible with that of DataExtension::extraStatics() in /home/content/31/9840731/html/event/framework/core/manifest/ClassLoader.php on line 82

Strict Standards: Declaration of SimpleWysiwygField::Field() should be compatible with that of FormField::Field() in /home/content/31/9840731/html/event/dataobject_manager/code/simple_wysiwyg_field/SimpleWysiwygField.php on line 4

Fatal error: CalendarSiteTree cannot be applied to SiteTree without being a DataExtension in /home/content/31/9840731/html/event/framework/core/Object.php on line 484

Looks like you're running DataObjectManager on an SS3 site? Yikes.

Yes,I looking for an Event management module.So i have installed event management module and their dependent modules dataobject manager,event_calendar,itemsetfiled,multiform,swfupload.

I am newbie for Silverstripe.Could please suggest me some workarounds...

None of those modules are compatible with SS3. The master branch of EventCalendar is updated for 3.0.

http://github.com/unclecheese/silverstripe-event-calendar

Or if you're using composer,

composer require silverstripe/event-calendar

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Thank you..