Agreement of Limited Partnership of EXCO Operating Company, LP



 Exhibit 4.21 

AGREEMENT OF 

LIMITED PARTNERSHIP OF 

EXCO PARTNERS OPERATING PARTNERSHIP, LP 

THIS AGREEMENT OF LIMITED PARTNERSHIP (this “Agreement”), dated as of September 29, 2006, is entered into
and executed by EXCO Partners OLP GP, LLC, a Delaware limited liability company, as general partner, and EXCO Resources, Inc., a Delaware corporation, as Organizational Limited Partner. 

ARTICLE I 

DEFINITIONS 

The following definitions shall for all purposes, unless otherwise clearly indicated to the contrary, apply to the terms used in this
Agreement. 
 “Certificate of Limited Partnership” means the Certificate of Limited Partnership filed with the
Secretary of State of the State of Delaware as described in the first sentence of Section 2.5 as amended or restated from time to time. 

“Delaware Act” means the Delaware revised Uniform Limited Partnership Act, as amended from time to time, and any
successor to such act. 
 “General Partner” means EXCO Partners OLP GP, LLC, a Delaware limited liability
company. 
 “Limited Partner” means the Organizational Limited Partner and any other limited partner admitted
to the Partnership from time to time. 
 “Organizational Limited Partner” means EXCO Resources, Inc., a
Delaware corporation.  
 “Partner” means the General Partner or any Limited Partner. 

“Partnership” means EXCO Partners Operating Partnership, LP, a Delaware limited partnership. 

“Percentage Interest” means, with respect to any Partner, the percentage of cash contributed by such Partner to the
Partnership as a percentage of all cash contributed by all the Partners to the Partnership. 
  

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 ARTICLE II 

ORGANIZATIONAL MATTERS 

2.1 Formation. Subject to the provisions of this Agreement, the General Partner and the Organizational Limited Partner have formed
the Partnership as a limited partnership pursuant to the provisions of the Delaware Act. The General Partner and the Organizational Limited Partner hereby enter into this Agreement to set forth the rights and obligations of the Partnership and
certain matters related thereto. Except as expressly provided herein to the contrary, the rights and obligations of the Partners and the administration, dissolution and termination of the Partnership shall be governed by the Delaware Act.

 2.2 Name. The name of the Partnership shall be, and the business of the Partnership shall be conducted under the name
of, “EXCO Partners Operating Partnership, LP”. 
 2.3 Principal Office; Registered Office. 

(a) The principal office of the Partnership shall be at 12377 Merit Drive, Suite 1700, LB82, Dallas, Texas 75251 or such
other place as the General Partner may from time to time designate. 
 (b) The address of the Partnership’s
registered office in the State of Delaware shall be the Corporation Trust Center, 1209 Orange Street, Wilmington, Delaware 19801, and the name of the Partnership’s registered agent for service of process at such address shall be the Corporation
Trust Center. 
 2.4 Term. The Partnership shall continue in existence until an election to dissolve the Partnership by
the General Partner. 
 2.5 Organizational Certificate. A Certificate of Limited Partnership of the Partnership has been
filed by the General Partner with the Secretary of State of the State of Delaware as required by the Delaware Act. The General Partner shall cause to be filed such other certificates or documents as may be required for the formation, operation and
qualification of a limited partnership in the State of Delaware and any state in which the Partnership may elect to do business. The General Partner shall thereafter file any necessary amendments to the Certificate of Limited Partnership and any
such other certificates and documents and do all things requisite to the maintenance of the Partnership as a limited partnership (or as a partnership in which the Limited Partners have limited liability) under the laws of Delaware and any state or
jurisdiction in which the Partnership may elect to do business. 
 2.6 Partnership Interests. Effective as of the date
hereof, the General Partner shall have a 0.001% Percentage Interest and the Organizational Limited Partner shall have a 99.999% Percentage Interest. 
  

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 ARTICLE III 

PURPOSE 

The purpose and business of the Partnership shall be to engage in any lawful activity for which limited partnerships may be organized
under the Delaware Act. 
 ARTICLE IV 

CAPITAL CONTRIBUTIONS 

At or about the date hereof, the Organizational Limited Partner contributed to the Partnership $999.99 in cash and the General Partner
contributed to the Partnership $0.01 in cash. 
 ARTICLE V 

ALLOCATIONS AND DISTRIBUTIONS 

5.1 Capital Accounts. The Partnership shall maintain a capital account for each of the Partners in accordance with the regulations
issued pursuant to Section 704 of the Internal Revenue Code of 1986, as amended (the “Code”), and as determined by the General Partner as consistent therewith. 

5.2 Allocations. For federal income tax purposes, each item of income, gain, loss, deduction and credit of the Partnership shall
be allocated among the Partners in accordance with their Percentage Interests, except that the General Partner shall have the authority to make such other allocations as are necessary and appropriate to comply with Section 704 of the Code and
the regulations pursuant thereto. 
 5.3 Distributions. From time to time, but not less often than quarterly, the General
Partner shall review the Partnership’s accounts to determine whether distributions are appropriate. The General Partner may make such cash distribution as it, in its sole discretion, may determine without being limited to current or accumulated
income or gains from any Partnership funds, including, without limitation, Partnership revenues, capital contributions or borrowed funds; provided, however, that no such distribution shall be made if, after giving effect thereto, the
liabilities of the Partnership exceed the fair market value of the assets of the Partnership. In its sole discretion, the General Partner may, subject to the foregoing proviso, also distribute to the Partners other Partnership property, or
other securities of the Partnership or other entities. All distributions by the General Partner shall be made in accordance with the Percentage Interests of the Partners. 

ARTICLE VI 

MANAGEMENT AND OPERATIONS OF BUSINESS 

Except as otherwise expressly provided in this Agreement, all powers to control and manage the business and affairs of the Partnership
shall be vested exclusively in the General Partner; the Limited Partner shall not have any power to control or manage the Partnership. 
  

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 ARTICLE VII 

RIGHTS AND OBLIGATIONS OF LIMITED PARTNER 

The Limited Partner shall have no liability under this Agreement except as provided in Article IV. 

ARTICLE VIII 

DISSOLUTION AND LIQUIDATION 

The Partnership shall be dissolved, and its affairs shall be wound up as provided in Section 2.4. 

ARTICLE IX 

AMENDMENT OF PARTNERSHIP AGREEMENT 

The General Partner may amend any provision of this Agreement without the consent of the Limited Partner and may execute, swear to,
acknowledge, deliver, file and record whatever documents may be required in connection therewith. 
 ARTICLE X 

GENERAL PROVISIONS 

10.1 Addresses and Notices. Any notice to the Partnership, the General Partner or the Limited Partner shall be deemed given if
received by it in writing at the principal office of the Partnership designated pursuant to Section 2.3(a). 
 10.2
Binding Effect. This Agreement shall be binding upon and inure to the benefit of the parties hereto and their successors and assigns. 

10.3 Integration. This Agreement constitutes the entire agreement among the parties pertaining to the subject matter hereof and
supersedes all prior agreements and understandings pertaining thereto. 
 10.4 Severability. If any provision of this
Agreement is or becomes invalid, illegal or unenforceable in any respect, the validity, legality and enforceability of the remaining provisions hereof, or of such provision in other respects, shall not be affected thereby. 

10.5 Applicable Law. This Agreement shall be governed by and construed and enforced in accordance with the laws of the State of
Delaware. 
  

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 IN WITNESS WHEREOF, this Agreement has been duly executed by the General Partner and
the Organizational Limited Partner as of September 29, 2006. 
  

			
	GENERAL PARTNER:
	
	EXCO Partners OLP GP, LLC
		
	By:	 	/s/ William L. Boeing
		 	Name: William L. Boeing
		 	Title:   Vice President, General Counsel and


  

			
	ORGANIZATIONAL LIMITED PARTNER:
	
	EXCO Resources, Inc.
		
	By:	 	/s/ William L. Boeing
		 	Name: William L. Boeing
		 	Title:   Vice President, General Counsel and


  

 [Signature Page to 

LP Agreement – EXCO Partners Operating Partnership, LP]