Mr. Gary Guidry reports

GRAN TIERRA ENERGY INC. ANNOUNCES CONSENT SOLICITATION FOR SENIOR SECURED AMORTIZING NOTES DUE 2031

Gran Tierra Energy Inc. is conducting a solicitation of consents from holders of its 9.750 per cent senior secured amortizing notes due 2031 to effect certain proposed amendments to the indenture dated as of Feb. 18, 2026, under which the notes were issued, pursuant to the terms and subject to the conditions set forth in the consent solicitation statement, dated Sept. 11, 2026.

As previously announced, on Aug. 5, 2026, the company entered into a share sale and purchase agreement (as it may be amended from time to time in accordance with its terms) with Etablissements Maurel et Prom SA, a company organized and existing under the laws of France (M&P), Maurel & Prom Andina SAS, a company organized and existing under the laws of France and an indirect wholly owned subsidiary of M&P (the purchaser), and the other parties thereto, whereby, among other things, Gran Tierra Energy International Holdings GmbH, a company organized and existing under the laws of Switzerland and an indirect wholly owned subsidiary of the company, has agreed to sell all of the issued and outstanding equity interests of Gran Tierra Energy CI GmbH, a company organized and existing under the laws of Switzerland and an indirect wholly owned subsidiary of the company (GTECI), to the purchaser (the transactions contemplated by the share purchase agreement, the sale). At completion (as defined in the share purchase agreement), among other things, the purchaser will assume the performance of every covenant and all obligations of the company under the indenture, the notes and the applicable collateral documents (to the extent not released).

The proposed amendments would: (i) enable the note assumption by releasing certain collateral, waiving debt coverage tests related to successor issuers for purposes of the sale and providing that the sale is not a change of control under the indenture; (ii) update the definition of GAAP (generally accepted accounting principles) in the indenture to include international financial reporting standards as issued and interpreted by the International Accounting Standards Board and accounting principles that are recognized as being generally accepted in France; (iii) update the financial reporting covenant, including to reflect that neither M&P nor the purchaser is an SEC-reporting (U.S. Securities and Exchange Commission) company and to permit the reporting of hydrocarbon proved reserve information pursuant to the Petroleum Resources Management System of the Society of Petroleum Engineers; and (iv) provide that certain acquisitions of working interests in the Sinu-9 gas licence in Colombia by the purchaser or any restricted subsidiary (as defined in the indenture) from certain affiliates of M&P will be considered a permitted investment under the indenture. No other changes will be made to the indenture or the notes. The interest rate, payment terms and maturity date of the notes will remain the same, and the notes will remain secured by a first-ranking pledge by GTECI in respect of all of the quotas and other equity securities of any kind of Gran Tierra Energy Colombia GmbH and Gran Tierra Operations Colombia GmbH.

The proposed amendments must be consented to by holders of not less than 50 per cent in aggregate principal amount of the notes outstanding (the requisite consents) in order to be effective.

Subject to the terms and conditions of this consent solicitation statement, the company is offering holders of notes who validly deliver (and do not validly revoke) their consents prior to the expiration time (as defined below) (each such holder a consenting holder) consent consideration equal to $2.50 (U.S.) per $1,000 (U.S.) in principal amount of notes held by such consenting holder, payable on the closing date of the sale.

Consummation of the consent solicitation and payment of the consent fee are conditioned upon the satisfaction or waiver of the conditions described in the consent solicitation statement, including, among other things, obtaining the requisite consents and the completion of the sale. If the requisite consents have not been obtained by the expiration time (as defined below), the company may, in its discretion and without limitation, extend the consent solicitation in order to seek to obtain the requisite consents or cause the other conditions to the consent solicitation to be satisfied.

Holders of the notes must validly deliver their consents at or prior to 5 p.m., New York time on Sept. 22, 2026, unless extended or earlier terminated by the company, in its sole discretion (such date and time, as the same may be extended or earlier terminated, the expiration time). A holder may validly revoke its consent prior to the earlier of the expiration time and the time of execution of the supplemental indenture (such date and time, as the same may be extended, the withdrawal deadline). Holders who deliver their consents at or prior to the expiration time (and do not validly revoke such consents at or before the withdrawal deadline) will be eligible to receive the consent fee.

If the requisite consents are received, it is expected that a supplemental indenture setting forth the proposed amendments will be entered into by the company, the note guarantors and the trustee promptly after receipt of such requisite consents, whether before or after the expiration time. The supplemental indenture will give effect to the proposed amendments and will be effective upon execution, but will only become operative on the closing date of the sale.

The company reserves the right to modify the consent solicitation statement and the terms and conditions of the consent solicitation or to terminate the consent solicitation.

BofA Securities Inc. is serving as sole solicitation agent in the consent solicitation and D.F. King & Co. Inc. has been retained to serve as the information and tabulation agent. Persons with questions regarding the consent solicitation should contact BofA Securities at 888-292-0070 (toll-free) or 646-855-8988 (collect). Requests for the consent solicitation statement should be directed to D.F. King & Co. at 888-548-6498 (toll-free) or 646-582-9168 (banks and brokers) or by e-mail at gte@dfking.com.

None of the company, the solicitation agent, the trustee under the indenture, or the information and tabulation agent makes any recommendation as to whether or not holders should deliver consents in the consent solicitation.

About Gran Tierra Energy Inc.

Gran Tierra Energy, together with its subsidiaries, is an independent international energy company currently focused on oil and natural gas exploration and production in Canada, Colombia, Ecuador and Azerbaijan. Upon completion of the sale described in this press release, the company's producing operations will be focused on Canada, and the company will continue to pursue its exploration interests in Azerbaijan and additional new growth opportunities that would further strengthen the company's portfolio. The company's common stock trades on the NYSE American, the Toronto Stock Exchange and the London Stock Exchange under the ticker symbol GTE.

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