Nebraska Revised Statute 21-2,183
Other remedies limited.
(MBCA 13.40) (a) The legality of a proposed or completed corporate action described in subsection (a) of section 21-2,172 may not be contested, nor may the corporate action be enjoined, set aside, or rescinded, in a legal or equitable proceeding by a shareholder after the shareholders have approved the corporate action.
(b) Subsection (a) of this section does not apply to a corporate action that:
(1) Was not authorized and approved in accordance with the applicable provisions of:
(ii) The articles of incorporation or bylaws; or
(iii) The resolution of the board of directors authorizing the corporate action;
(2) Was procured as a result of fraud, a material misrepresentation, or an omission of a material fact necessary to make statements made, in light of the circumstances in which they were made, not misleading;
(3) Is an interested transaction, unless it has been recommended by the board of directors in the same manner as is provided in section 21-2,122 and has been approved by the shareholders in the same manner as is provided in section 21-2,123 as if the interested transaction were a director's conflicting interest transaction; or
(4) Is approved by less than unanimous consent of the voting shareholders pursuant to section 21-256 if:
(i) The challenge to the corporate action is brought by a shareholder who did not consent and as to whom notice of the approval of the corporate action was not effective at least ten days before the corporate action was effected; and
(ii) The proceeding challenging the corporate action is commenced within ten days after notice of the approval of the corporate action is effective as to the shareholder bringing the proceeding.