UNITED STATES
SECURITIES AND EXCHANGE COMMISSION

Washington,
D.C. 20549



FORM
10-K/A

(Amendment
No. 1)



(Mark
One)



| | ☒ | ANNUAL
                                                                                                                              REPORT
                                                                                                                              PURSUANT
                                                                                                                              TO
                                                                                                                              SECTION
                                                                                                                              13
                                                                                                                              OR
                                                                                                                              15(d)
                                                                                                                              OF
                                                                                                                              THE
                                                                                                                              SECURITIES
                                                                                                                              EXCHANGE
                                                                                                                              ACT
                                                                                                                              OF
                                                                                                                              1934
| | - | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------



For
the fiscal year ended December 31, 2018
or



| | ☐ | TRANSITION
                                                                                                                              REPORT
                                                                                                                              PURSUANT
                                                                                                                              TO
                                                                                                                              SECTION
                                                                                                                              13
                                                                                                                              OR
                                                                                                                              15(d)
                                                                                                                              OF
                                                                                                                              THE
                                                                                                                              SECURITIES
                                                                                                                              EXCHANGE
                                                                                                                              ACT
                                                                                                                              OF
                                                                                                                              1934
| | - | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------



For
the transition period from _____ to _____
Commission file number of the issuing entity: 333-179413-01



Central
Index Key Number of the issuing entity: 0001571238

UBS-Barclays
Commercial Mortgage Trust 2013-C6

(exact
name of the issuing entity as specified in its charter)



Central
Index Key Number of the depositor: 0001541480

Barclays
Commercial Mortgage Securities LLC

(exact
name of the depositor as specified in its charter)



Central
Index Key Number of the sponsor: 0000312070

Barclays
Bank PLC

(exact
name of the sponsor as specified in its charter)



Central
Index Key Number of the sponsor: 0001541886

UBS
Real Estate Securities Inc.

(exact
name of the sponsor as specified in its charter)



Central
Index Key Number of the sponsor: 0001567746

Redwood
Commercial Mortgage Corporation

(exact
name of the sponsor as specified in its charter)



Central
Index Key Number of the sponsor: 0001542256

Natixis
Real Estate Capital LLC

(exact
name of the sponsor as specified in its charter)



|New
    York(State or other jurisdiction ofincorporation or organization ofthe issuing entity) | 27-010880(I.R.S. EmployerIdentification Number)
|---------------------------------------------------------------------------------------------- | -----------------------------------------------



c/o
U.S. Bank National Association

as
Certificate Administrator

190
S. LaSalle Street

Chicago,
IL

(Address
of principal executive offices of the issuing entity)



60603

(Zip
Code)



Registrant’s
telephone number, including area code:

(212)
412-4000



Securities
registered pursuant to Section 12(b) of the Act: None.



Securities
registered pursuant to Section 12(g) of the Act: None.



Indicate
by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act. ☐  Yes  ☒  No



Indicate
by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the Act. ☐  Yes  ☒  No



Indicate
by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange
Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports),
and (2) has been subject to such filing requirements for the past 90 days.  ☒  Yes  ☐  No



Indicate
by check mark whether the registrant has submitted electronically and posted on its corporate Web site, if any, every Interactive
Data File required to be submitted and posted pursuant to Rule 405 of Regulation S-T (Section 232.405 of this chapter) during
the preceding 12 months (or for such shorter period that the registrant was required to submit and post such files).



Not
applicable.



Indicate
by check mark if disclosure of delinquent filers pursuant to Item 405 of Regulation S-K (Section 229.405 of this chapter) is not
contained herein, and will not be contained, to the best of registrant’s knowledge, in definitive proxy or information statements
incorporated by reference in Part III of this Form 10-K or any amendment to this Form 10-K.



Not
applicable.



Indicate
by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting
company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,”
“smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act.





|Large accelerated
    filer | ☐                                                    | Accelerated filer         | ☐
|--------------------------- | ---------------------------------------------------- | ------------------------- | -
|                            |                                                      |                           |  
|Non-accelerated filer       | ☒  (Do not check
    if a smaller reporting company) | Smaller reporting company | ☐
|                            |                                                      |                           |  
|                            |                                                      | Emerging growth company   | ☐



If an
emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying
with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act.  ☐



Indicate
by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Act).  ☐  Yes  ☒  No



State
the aggregate market value of the voting and non-voting common equity held by non-affiliates computed by reference to the price
at which the common equity was last sold, or the average bid and asked price of such common equity, as of the last business day
of the registrant’s most recently completed second fiscal quarter.



Not
applicable.



Indicate
by check mark whether the registrant has filed all documents and reports required to be filed by Section 12, 13 or 15(d) of the
Securities Exchange Act of 1934 subsequent to the distribution of securities under a plan confirmed by a court. ☐  Yes  ☐  No



Not
applicable.



Indicate
the number of shares outstanding of each of the registrant’s classes of common stock, as of the latest practicable date.



Not
applicable.



DOCUMENTS
INCORPORATED BY REFERENCE



List hereunder
the following documents if incorporated by reference and the Part of the Form 10-K (e.g., Part I, Part II, etc.) into which the
document is incorporated: (1) Any annual report to security holders; (2) Any proxy or information statement; and (3) Any prospectus
filed pursuant to Rule 424(b) or (c) under the Securities Act of 1933. The listed documents should be clearly described for identification
purposes (e.g., annual report to security holders for fiscal year ended December 24, 1980).



Notapplicable.










EXPLANATORY NOTES



The sole purpose of this Amendment No. 1 to our Annual Report on
Form 10-K for the fiscal year ended December 31, 2018 filed with the Securities and Exchange Commission on March 26, 2019 (the
“Original Form 10-K”) is to replace the report on assessment of compliance and the accountants’ attestation
report of Rialto Capital Advisors, LLC filed as exhibits to the Original Form 10-K under Exhibit 33 and Exhibit 34, respectively,
with the corresponding exhibits attached hereto. Except as described above, no other changes are being made to the Original Form
10-K.



Pursuant to Rule 12b-15 under the Securities Exchange Act of 1934,
as amended, this Form 10-K/A also contains new certifications pursuant to Section 302 of the Sarbanes-Oxley Act of 2002, which
are attached hereto.



PART IV



Item 15. Exhibits, Financial Statement Schedules



|31   | Rule 13a-14(d)/15d-14(d) Certifications.                                                            
|---- | ----------------------------------------------------------------------------------------------------
|     |                                                                                                     
|33   | Reports on assessment of compliance with servicing criteria for asset-backed securities.            
|     |                                                                                                     
|33.2 | Rialto Capital Advisors, LLC, as Special Servicer                                                   
|     |                                                                                                     
|34   | Attestation reports on assessment of compliance with servicing criteria for asset-backed securities.
|     |                                                                                                     
|34.2 | Rialto Capital Advisors, LLC, as Special Servicer                                                   



SIGNATURES



Pursuant to the requirements of Section 13 or 15(d) of the Securities
Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly
authorized.



Barclays Commercial Mortgage Securities LLC
(Depositor)



|/s/ Daniel Vinson                                                                                   | 
|--------------------------------------------------------------------------------------------------- | 
|Daniel Vinson, Chief Executive Officer(senior officer in charge of securitization of the depositor) | 



Date: November 5, 2019