XF 2.1 .m-pageWidth is undefined in anonymous-file-0.less Error

Hello, what could be the cause of this error?

Code:
Less_Exception_Compiler: .m-pageWidth is undefined in anonymous-file-0.less src/vendor/oyejorge/less.php/lib/Less/Tree/Mixin/Call.php:148

Code:
#0 src/vendor/oyejorge/less.php/lib/Less/Tree/Ruleset.php(147): Less_Tree_Mixin_Call->compile(Object(Less_Environment))
#1 src/vendor/oyejorge/less.php/lib/Less/Tree/Ruleset.php(88): Less_Tree_Ruleset->EvalMixinCalls(Object(Less_Tree_Ruleset), Object(Less_Environment), 2)
#2 src/vendor/oyejorge/less.php/lib/Less/Tree/Ruleset.php(94): Less_Tree_Ruleset->compile(Object(Less_Environment))
#3 src/vendor/oyejorge/less.php/lib/Less/Parser.php(199): Less_Tree_Ruleset->compile(Object(Less_Environment))
#4 src/XF/CssRenderer.php(394): Less_Parser->getCss()
#5 src/XF/CssRenderer.php(342): XF\CssRenderer->renderToCss('public:xb_foote...', '// Note that th...')
#6 src/XF/CssRenderer.php(250): XF\CssRenderer->renderTemplate('public:xb_foote...', NULL)
#7 src/XF/CssRenderer.php(116): XF\CssRenderer->renderTemplates(Array, Array, Array)
#8 src/XF/CssWriter.php(53): XF\CssRenderer->render(Array)
#9 css.php(30): XF\CssWriter->run(Array, 3, 2, '5bd2c10671f179b...')
#10 {main}

Code:
array(4) {
  ["url"] => string(254) "/css.php?css=public%3AUserActivity.less%2Cpublic%3Abb_code.less%2Cpublic%3Amessage.less%2Cpublic%3Anotices.less%2Cpublic%3Ashare_controls.less%2Cpublic%3Axb_footer.less%2Cpublic%3Aextra.less&s=3&l=2&d=1532365507&k=5bd2c10671f179b75745ffd58602f1c475942a1d"
  ["referrer"] => string(104) "https://xxxxxxxxxxxxxxxxxxxx"
  ["_GET"] => array(5) {
    ["css"] => string(151) "public:UserActivity.less,public:bb_code.less,public:message.less,public:notices.less,public:share_controls.less,public:xb_footer.less,public:extra.less"
    ["s"] => string(1) "3"
    ["l"] => string(1) "2"
    ["d"] => string(10) "1532365507"
    ["k"] => string(40) "5bd2c10671f179b75745ffd58602f1c475942a1d"
  }
  ["_POST"] => array(0) {
  }
}
 
What's the content of Template xb_footer.less?

Content in this way
Code:
.footer-stretched > div
{
    padding-left: 0;
    padding-right: 0;
}
.xb-footer-block .p-header-logo
{
    max-width: none;
}
.p-footer-default
{
    .xf-publicFooter();

    a
    {
        .xf-publicFooterLink();
    }
    .p-body & { margin-top: @xf-paddingLargest; }
}
.p-footer-inner
{
    .m-pageWidth();
    .p-body & { max-width: 100% !important; padding-right: 0; padding-left: 0; }
}

.p-footer-row
{
    .m-clearFix();
}

.p-footer-row-main
{
    float: left;
}

.p-footer-row-opposite
{
    float: right;
}

.p-footer-linkList
{
    .m-listPlain();
    .m-clearFix();

    > li
    {
        float: left;
        margin-right: .5em;

        &:last-child
        {
            margin-right: 0;
        }

        a
        {
            padding: 2px 4px;
            border-radius: @xf-borderRadiusSmall;

            &:hover
            {
                text-decoration: none;
                background-color: fade(@xf-publicFooterLink--color, 10%);
            }
        }
    }
}

.p-footer-rssLink
{
    > span
    {
        position: relative;
        top: -1px;

        display: inline-block;
        width: 1.44em;
        height: 1.44em;
        line-height: 1.44em;
        text-align: center;
        font-size: .8em;
        background-color: #FFA500;
        border-radius: 2px;
    }

    .fa-rss
    {
        color: white;
    }
}

.p-footer-copyright
{
    .xf-xbCopyrightCSS();
    .p-pe-copyright a
    {
        color: @xf-xbCopyrightCSS--color;
    }
    .p-footer-debug
    {
        margin-top: 10px;
        a { color: @xf-xbCopyrightCSS--color; }
        .pairs > dt { color: inherit; }
    }
    .p-footer-default { font-size: @xf-xbCopyrightCSS--font-size; }
}
.p-footer--container
{
    .m-clearFix();
}
.p-footer-row-main
{
    margin-right: .5em;
}
.p-footer-linkList .shareButtons--iconic .shareButtons-button
{
    font-size: @xf-fontSizeSmall;
    line-height: 1;
}
<xf:if is="property('xbFooterLocation') == 'copyright'">
.p-footer-copyright--flex
{
    display: flex;
    flex-wrap: wrap;
    justify-content: space-between;
    align-items: center;
    width: 100%;
    .copyright-right { margin-left: auto; }
    .p-footer-default
    {
        background: none;
        border-width: 0;
        padding: 0 !important;
        .p-footer-inner
        {
            max-width: 100% !important;
            padding: 0 !important;
            > * { float: none; }
        }
        
    }
}
@media (max-width: @xf-responsiveWide)
{
    .p-footer--container
    {
        .p-footer-copyright--flex
        {
            display: block;
        }
    }
}
</xf:if>
<xf:if is="!property('xbStretchFooter')">
.p-footer--container
{
    max-width: @xf-pageWidthMax;
    margin: 0 auto;
    padding: 0 @xf-pageEdgeSpacer;
    .p-footer-inner
    {
        max-width: 100%;
        padding: 0;
    }
    .ForumStyleClassic &
    {
        padding: 0;
    }
}
@media (max-width: @xf-responsiveEdgeSpacerRemoval)
{
    .XenBase .p-footer--container
    {
        padding: 0;
    }
}
</xf:if>


<xf:if is="property('xbFooterLocation') == 'copyright'">
@footer_responsive: @xf-responsiveWide;
<xf:else />
@footer_responsive: @xf-responsiveMedium;
</xf:if>
@media (max-width: @footer_responsive)
{
    .p-footer--container
    {
        .p-footer-default, .p-footer-custom, .p-footer-copyright
        {
            padding-left: 10px;
            padding-right: 10px;
            font-size: @xf-fontSizeSmaller;
            .p-footer-inner
            {
                padding-right: 0;
                padding-left: 0;
            }
            .p-footer-linkList > li a
            {
                padding-left: 0;
            }
        }
        .p-footer-copyright .p-footer-debug
        {
            text-align: left;
            margin-top: 10px;
        }
        .copyright-right
        {
            margin-top: 10px;
        }
    }
    .p-footer-row-main
    {
        margin-bottom: 10px;
    }
    .p-footer-row-main,
    .p-footer-row-opposite
    {
        float: none;
    }


    .p-footer-copyright
    {
        text-align: left;
        padding: 10px 5px; // aligns with other links
    }
}
@media (max-width: @xf-responsiveNarrow)
{
    .p-footer--container
    {
        .p-footer-default, .p-footer-custom, .p-footer-copyright
        {
            padding-left: 10px;
            padding-right: 10px;
            .p-footer-inner
            {
                padding-right: 0;
                padding-left: 0;
            }
            .p-footer-linkList > li a
            {
                padding-left: 0;
            }
        }
        span.p-pe-copyright
        {
            display: block;
            margin-top: 10px;
        }
    }
}
@media (min-width: (@xf-responsiveMedium + 1))
{
    .ForumStyleBoxed .footer-stretched > div
    {
        padding-right: @xf-paddingLargest;
        padding-left: @xf-paddingLargest;
    }    
}
@media (max-width: @xf-responsiveEdgeSpacerRemoval)
{
    .p-body .p-footer-default
    {
        margin-right: -@xf-pageEdgeSpacer;
        margin-left: -@xf-pageEdgeSpacer;
    }
}

<xf:if is="{{ property('xbFooter') }}">
.p-footer-custom
{    
    .xf-xbCustomFooterCSS();
    .xb-footer--wrapper
    {
    display: flex;
    flex-wrap: wrap;
    align-items: stretch;
    width: auto;
    }
    a
    {
        color: @xf-xbCustomFooterLinks--color;
    }
    <xf:if is="property('xbShareIconStyle') == 'circle' OR property('xbShareIconStyle') == 'blocked'">
    a.shareButtons-button
    {
        color: #FFF;
    }
    </xf:if>
        .xb-footer-block
        {
            .xf-xbCustomFooterBlock();
                &:first-child
                {
                    padding-left: 0;
                    border-left-width: 0;
                }
                &:last-child
                {
                    padding-right: 0;
                    border-right-width: 0;
                }
                h3
                {
                    .xf-xbFooterHeaders();
                    a
                    {
                        color: @xf-xbFooterHeaders--color;
                    }
                }
                p
                {
                    line-height: 1.8;
                }
                ul
                {
                    list-style-type: none;
                    padding-left: 0;
                    li a
                    {
                        padding: 12px 0;
                        display: inline-block;
                        .m-transition();
                        .xf-xbCustomFooterLinks();
                        &.avatar:hover
                        {
                            padding: 0;
                        }
                        &:hover
                        {
                            .xf-xbCustomFooterLinksHover();
                        }
                    }
                    li > i
                    {
                        .xf-xbCustomFooterIcon();
                    }
                    li:last-child a
                    {
                        border-bottom-width: 0;
                        padding-bottom: 0;
                    }
                    li:first-child a
                    {
                        border-top-width: 0;
                        padding-top: 0;
                    }
                }
                .block-container
                {
                    background-color: transparent;
                    border-width: 0;
                    box-shadow: none;
                    a
                    {
                        padding: 0;
                        &.shareButtons-button
                        {
                            padding: 6px;
                        }
                    }
                    > *
                    {
                        padding-left: 0;
                        padding-right: 0;
                    }
                    .block-body
                    {
                        .xf-xbFooterBlockBody();
                    }
                    .block-row
                    {
                        padding: 0;
                    }
                }
            .pairs
            {
                padding: 12px 0;
                > dt
                {
                    color: @xf-xbCustomFooterCSS--color;
                }
            }
            .block-footer
            {
                background: none;
                border-width: 0;
            }
        }
        .xb-footer-block-1
        {
            width: @xf-xbFooterBlock1Width;
        }
        .xb-footer-block-2
        {
            width: @xf-xbFooterBlock2Width;
        }
        .xb-footer-block-3
        {
            width: @xf-xbFooterBlock3Width;
        }
        .xb-footer-block-4
        {
            width: @xf-xbFooterBlock4Width;
        }
}
.p-footer-social
{
    
    margin: @xf-elementSpacer auto;
    padding: (@xf-elementSpacer + @xf-xbCustomFooterCSS--padding) 0;
    text-align: center;
    border-top: 1px solid xf-diminish(@xf-xbCustomFooterCSS--background-color, 5%);
    border-bottom: 1px solid xf-diminish(@xf-xbCustomFooterCSS--background-color, 5%);
    &.p-footer-socialTop { border-top-width: 0px; padding-top: 0; }
    &.p-footer-socialBottom { border-bottom-width: 0; padding-bottom: 0;  }
    a { float: none; display: inline-block; }
    h3 { margin-top: 0; padding-top: 0; font-size: @xf-fontSizeLargest; }
}
@media (max-width: @xf-responsiveWide)
{
    .XenBase .xb-footer-block
    {
        margin: 0 ((@xf-pageEdgeSpacer) / 2) @xf-elementSpacer;
        min-width: @xf-sidebarWidth;
        flex: 1 1 @xf-sidebarWidth;
        padding: 0;
        h3 { margin-top: 0; }
    }
}
@media (max-width: @xf-responsiveMedium)
{
    .XenBase .xb-footer-block
    {
        flex: 1 1 100%;
        padding-right: 0;
        margin: 0;
        padding-left: 0;
        .block-container
        {
            margin-left: 0;
            margin-right: 0;
        }
    }
    <xf:if is="{{ property('xbDisableResponsive') }}">
    .XenBase .p-footer-custom
    {
        display: none;
    }
    </xf:if>
}
</xf:if>
 
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