Exhibit 10.6

DECHERT DRAFT 4/23/21

FS CREIT Finance BB-1 LLC

201 Rouse Boulevard

Philadelphia, PA 19112

April 23, 2021

Barclays Bank PLC

745 7th Avenue

New York, New York 10019

Attention: Francis X. Gilhool, Jr.

Re: Master Repurchase Agreement, dated as of February 22, 201 (as the same has been and may be amended, modified, restated, replaced, waived, substituted, supplemented or extended and in effect from time to time, the “Repurchase Agreement”), by and between FS CREIT Finance BB-1 LLC, a Delaware limited liability company(“Seller”), and Barclays Bank PLC, a public limited company organized under the laws of England and Wales (“Purchaser”)

To the addressee above:

Pursuant to the definition of “Maximum Facility Purchase Price” in Section 1 of that certain Fee Letter, dated as of February 22, 2021 (as the same may be amended, modified, restated, replaced, waived, substituted, supplement or extended and in effect from time to time, the “Fee Letter”), from Purchaser and accepted and agreed by Seller, entered into in connection with the Repurchase Agreement, Seller hereby requests that the Maximum Facility Purchase Price be increased by $828,074.80 up to an aggregate total of $175,828,074.80.

Please evidence your agreement to increase the Maximum Facility Purchase Price in accordance with the above request by returning a countersigned copy of this letter to Seller.

THIS LETTER AGREEMENT (AND ANY CLAIM OR CONTROVERSY HEREUNDER) SHALL BE CONSTRUED IN ACCORDANCE WITH THE LAWS OF THE STATE OF NEW YORK, AND THE OBLIGATIONS, RIGHTS, AND REMEDIES OF THE PARTIES HEREUNDER SHALL BE DETERMINED IN ACCORDANCE WITH SUCH LAWS WITHOUT REGARD TO THE CONFLICT OF LAWS DOCTRINE APPLIED IN SUCH STATE (OTHER THAN SECTION 5-1401 OF THE GENERAL OBLIGATIONS LAW OF THE STATE OF NEW YORK).

This letter agreement may be executed in counterparts, each of which so executed shall be deemed to be an original, but all of such counterparts shall together constitute but one and the same instrument. Signature pages to this letter agreement delivered in electronic form (such as PDF) shall be considered binding with the same force and effect as original signatures.

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Please acknowledge your acceptance of the terms and conditions presented in this letter agreement by signing in the place indicated below.

By signing below, FS Credit Real Estate Income Trust, Inc., a Maryland corporation (“Guarantor”), hereby acknowledges the foregoing letter and in connection Purchaser’s agreement to the terms of the foregoing letter reaffirms the terms and conditions of that certain Guaranty, dated as of February 22, 2021 (as the same may be amended, modified, restated, replaced, waived, substituted, supplemented or extended and in effect from time to time, the “Guaranty”), made by Guarantor for the benefit of Purchaser, and acknowledges and agrees that the Guaranty remains in full force and effect.

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Barclays-FS CREIT – Upsize Letter

Barclays-FS CREIT – Upsize Letter