EXHIBIT 10.4

COMMITMENT INCREASE SUPPLEMENT

April 30, 2026

The Bank of Nova Scotia as Administrative Agent

250 Vesey Street, 24th Floor New York, New York 10281 Attention: U.S. Fund Finance

Email: usfundfinance@scotiabank.com

Re: John Hancock Comvest Private Income Fund (the “Company”) Ladies and Gentlemen:

We refer to that certain Senior Secured Revolving Credit Agreement, dated as of December 2, 2025 (as amended, restated, supplemented, amended and restated, or otherwise modified from time to time, the “Credit Agreement”; capitalized terms used in this Response Letter (as defined below) and not otherwise defined have the meanings for such terms set forth in the Credit Agreement), by and among the Company, the Lenders and Issuing Banks from time to time party thereto and The Bank of Nova Scotia, as Administrative Agent (in such capacity, the “Administrative Agent”).

Pursuant to Section 2.08(e) of the Credit Agreement, we deliver this response (this “Response Letter”) to confirm that each of the Company and Pinnacle Bank, a Tennessee Bank, d/b/a Synovus Bank (the “Assuming Lender”) agrees that, effective upon the satisfaction of the conditions set forth in Sections 2.08(e)(i) and (ii) of the Credit Agreement (the “Commitment Increase Date”), the Assuming Lender will (and does hereby) become a “Lender” under and for all purposes of the Credit Agreement with a Multicurrency Commitment equal to $75,000,0001. Without limiting the foregoing, the Assuming Lender hereby agrees to be bound by and comply with all of the terms and provisions of the Credit Agreement applicable to it as a “Lender” thereunder and that it will perform in accordance with its terms all of the obligations which by the terms of the Credit Agreement are required to be performed by it as a Lender. The Assuming Lender represents and warrants that it has full power and authority, and has taken all action necessary, to execute and deliver this Response Letter and to consummate the transactions contemplated hereby and to become a Lender under the Credit Agreement. Pursuant to Section 2.08(e) of the Credit Agreement, we deliver this response (this “Response Letter”) to confirm that each of the Company and The Bank of Nova Scotia (the “Existing Lender”) agrees that, effective upon the satisfaction of the conditions set forth in Sections 2.08(e)(i) and (ii) of the Credit Agreement, the Multicurrency Commitment of the Existing Lender under the Credit Agreement shall be decreased from $150,000,000 to

$112,500,0002 as of the date hereof and the total Multicurrency Commitment of all Lenders under the Credit Agreement shall be increased from $150,000,000 to $187,500,000. The Existing Lender represents and warrants that it has full power and authority, and has taken all action necessary, to execute and deliver this Response Letter and to consummate the transactions contemplated hereby

1 $37,500,000 constituting Temporary Commitment and $37,500,000 constituting Permanent Commitment.

2 $56,250,000 constituting Temporary Commitment and $56,250,000 constituting Permanent Commitment.

including, without limitation, the decrease of the Existing Lender’s Multicurrency Commitment from

$150,000,000 to $112,500,000.

This Response Letter shall be binding upon, and inure to the benefit of, the parties hereto and their respective successors and permitted assigns. This Response Letter may be executed in any number of counterparts, which together shall constitute one instrument. Delivery of an executed counterpart of a signature page of this Response Letter by email or other electronic method of transmission (e.g., PDF) shall be effective as delivery of a manually executed counterpart of this Response Letter. This Response Letter shall be governed by, and construed in accordance with, the laws of the State of New York. The parties hereto hereby agree that this Response Letter is a Loan Document.

[Remainder of Page Intentionally Left Blank]

Very truly yours,

PINNACLE BANK, A TENNESSEE BANK, D/B/A SYNOVUS BANK,

as Assuming Lender

By: /s/ Ricardo Escobedo

Name: Ricardo Escobedo

Title: Director

THE BANK OF NOVA SCOTIA,

as Existing Lender

By: /s/ Aron Lau

Name: Aron Lau

Title: Director

By: /s/ Erica He

Name: Erica He

Title: Director

JOHN HANCOCK COMVEST PRIVATE INCOME FUND

By: /s/ Cecilio Rodriguez

Name: Cecilio Rodriguez

Title: Chief Financial Officer

ACKNOWLEDGED, ACCEPTED CONSENTED AND AGREED:

THE BANK OF NOVA SCOTIA,

as Administrative Agent

By: /s/ Aron Lau

Name: Aron Lau

Title: Director

By: /s/ Erica He

Name: Erica He

Title: Director