Exhibit 4.2


 


AMENDMENT
NO. 3 TO AMENDMENT AGREEMENT AND WAIVER


 


This
AMENDMENT NO. 3 TO AMENDMENT AGREEMENT AND WAIVER (the “Amendment”), dated as of March 28, 2019, is
made by and between Ener-Core, Inc., a Delaware corporation, with headquarters located at 30100 Town Center Dr., Suite O-209,
Laguna Niguel, California 92677 (the “Company”), and the investor listed on the signature page attached
hereto (the “Holder”).


 


RECITALS


 


A. Reference
is made to that certain Securities Purchase Agreement dated as of November 23, 2016, by and among the Company, the Holder and
the other investors listed on the signature pages attached thereto and party to a joinder agreement thereto (the “November
2016 SPA”); and the Senior Secured Notes issued to the Holder pursuant thereto (as amended from time to time prior to
the date hereof, the “November 2016 Notes”);


 


B. Reference
is made to that certain Amendment Agreement and Waiver dated as of December 31, 2018 by and among the Company and the Holder with
respect to the November 2016 SPA and the December 2016 Notes (the “December Amendment”); and


 


C. In
compliance with Section 15 of the November 2016 Notes and the November 2016 SPA, this Amendment shall only be effective upon the
execution and delivery of this Amendment and agreements in form and substance identical to this Amendment (other than with respect
to the identity of the Holder and any provision regarding the reimbursement of legal fees) (together with this Amendment, the
“Amendments”) by other holders of the November 2016 Notes representing at least the Required Holders (as defined
in each of the November 2016 Notes) (such time, the “Effective Time”).


 


AGREEMENT


 


NOW
THEREFORE, in consideration of the foregoing mutual premises and the covenants and agreements hereinafter set forth, and for
other good and valuable consideration, the receipt, and legal adequacy of which is hereby acknowledged, the parties hereto, intending
to be legally bound, hereby agree as follows:


 


ARTICLE
I


AMENDMENT


 


1. Amendment
of December Amendment. All references to the date “January 31, 2019” set forth in the December Amendment are hereby
amended to instead refer to the date “April 30, 2019”, and all references to the date “February 1, 2019” set
forth in the December Amendment are hereby amended to instead refer to the date “May 1, 2019”. Capitalized terms used
herein and not otherwise defined herein shall have the respective meanings set forth in the December Amendment.


 


ARTICLE
II

MISCELLANEOUS


 


1. Effect
of this Amendment. This Amendment shall form a part of the November 2016 Notes for all purposes, and each holder of November
2016 Notes shall be bound hereby. This Amendment shall only be deemed to be in full force and effect from and after both the execution
of this Amendment by the parties hereto and the execution of Amendments substantially identical to this Amendment by the Company
and “Holders” holding at least a majority of the aggregate principal amount of the November 2016 Notes outstanding,
including the Lead Investor, as well as the Collateral Agent, that, together with undersigned, constitute the Required Holders.
From and after such effectiveness, any reference to the November 2016 Notes shall be deemed to be a reference to the November
2016 Notes, as amended hereby. Except as specifically amended as set forth herein, each term and condition of the November 2016
Notes shall continue in full force and effect.


 






     


     


    

 


2. Entire
Agreement. This Amendment, together with the November 2016 SPA and November 2016 Notes, as amended to date, contains the entire
agreement of the parties with respect to the matters contemplated hereby and thereby, and supersedes any prior or contemporaneous
written or oral agreements between them concerning the subject matter of this Amendment.


 


3. Governing
Law. This Amendment shall be governed by the internal law of the State of New York.


 


4. Counterparts.
This Amendment may be executed in any number of counterparts and by different parties hereto in separate counterparts, each of
which when so executed and delivered shall be deemed an original, but all such counterparts together shall constitute but one
and the same instrument; signature pages may be detached from multiple separate counterparts and attached to a single counterpart
so that all signature pages are physically attached to the same document. This Amendment may be executed by fax or electronic
mail, in PDF format, and no party hereto may contest this Amendment’s validity solely because a signature was faxed or otherwise
sent electronically.


 


[Signature
Page Follows]


 




    2


     


    

 


IN
WITNESS WHEREOF, the Holder and the Company have caused their respective signature pages to this Amendment to be duly executed
as of the date first written above.


 


	 	COMPANY:
	 	 
	 	ENER-CORE,
    INC.
	 	 	 
	 	By:	
	 	 	Name:	Domonic
    J. Carney
	 	 	Title: 	Chief
    Financial Officer


 


Signature
Page to amendment no. 3 to Amendment Agreement and Waiver—2016 Notes 


 




     


     


    

 


IN
WITNESS WHEREOF, the Holder and the Company have caused their respective signature pages to this Amendment to be duly executed
as of the date first written above.


 





	 	HOLDER:
	 	 
	 	By:	

	 	 	Name: 	 


 


Signature
Page to amendment no. 3 to Amendment Agreement and Waiver—2016 Notes