Recently while importing a solution from dev environment to test environment we were getting this error.
This error occurs when we have some kind of mismatch among the attribute in both the environment for e.g. same attribute is created in both the environment with different datatype.
After comparing the dev and test environment, we realized that the Schema Name for one of the field was different in dev environment.
i.e. lss_Client_agress_to_LSSContract in test and lss_client_agress_to_lsscontract in dev
So we removed the field from form and deleted it in our dev environment.
After that import worked properly.
Hope this helps