Things like this does not happen very often and the main reason is that not many people work on Land Desktop projects anymore. But, only last week I have seen at least two customers with this issue. So what is the issue- you may ask? The issue is that some customers wanted to import the entire Land Desktop project into Civil 3D and as you all know by now, that's not really a problem anymore, since there is a command (found in Insert ribbon) that does just that – imports Land Desktop Project. This is why our user did and instead of nicely converted drawing he received a greeting one or more pIAlignments is Null! Errors or some other variation of the <object> is Null! error. To make thing more interesting it did not happen to all files or templates.
Why is this happening? Not sure about all possible reasons this error may occur but I am sure about the one. The Civil 3D template file may be having missing defaults or default styles.
As I mentioned before, this may happen to other object types but I will use alignment to make my point clear. If we go into Settings tab, expand Alignment and go into Edit Feature Settings you may see where the problem lies. Here are the steps:
1. Open your troubled drawing template
2. In Settings tab, right-click on Alignment node and choose Edit Feature Settings
3. Expand Default Styles section and make sure Alignment (and other object types) has Styles and other defaults assigned. Empty entries, <none> or overrides may indicate possible problem.
4. Set defaults and apply changes
5. Then try to import Land Desktop project into Civil 3D
I hope this helps.