Unwanted query string showing up in loop, but only once (RSS)

[seezee]

I made a template to handle my RSS feed. The url attribute in the <enclosure/> tag has a mysterious query string inserted between the equal sign and the actual URL, but only for the most recent post — it works correctly for all older posts. I can't figure out where this is coming from.

The image path comes from the post meta, e.g., if this is about.md:

---
layout: _main.njk
title: About This Site
permalink: "/about/"
ogtype: website
image: /assets/images/site/logo.webp
---

The image is "/assets/images/site/logo.webp"

My RSS template looks like this:

---json
{
  "permalink": "rss.xml",
  "eleventyExcludeFromCollections": true,
  "metadata": {
    "title": "My Website",
    "description": "A description",
    "language": "en-US",
    "base": "https://my.web.site",
    "author": {
      "name": "Joe Blow"
    },
    "siteImage": "assets/images/site/logo.png"
  }
}
---
<?xml version="1.0" encoding="utf-8"?>
<rss version="2.0" xmlns:dc="http://purl.org/dc/elements/1.1/" xml:base="{{ metadata.base | addPathPrefixToFullUrl }}" xmlns:atom="https://www.w3.org/2005/Atom">
  <channel>
    <title><![CDATA[{{ metadata.title }}]]></title>
    <link>{{ metadata.base | addPathPrefixToFullUrl }}</link>
    <atom:link href="{{ permalink | htmlBaseUrl(metadata.base) }}" rel="self" type="application/rss+xml" />
    <description><![CDATA[{{ metadata.description }}]]></description>
    <language>{{ metadata.language or page.lang }}</language>
    <category>Photography, Blog</category>
    <copyright>Copyright © 2012{{ helpers.currentYearRSS() | safe }} {{ metadata.author.name }}. All rights reserved.</copyright>
    <image>
      <url>{{ metadata.base | addPathPrefixToFullUrl }}{{ metadata.siteImage }}</url>
      <title><![CDATA[{{ metadata.title }}]]></title>
      <link>{{ metadata.base | addPathPrefixToFullUrl }}</link>
      <description><![CDATA[{{ metadata.description }}]]></description>
      <width>144</width>
      <height>144</height>
    </image>
    {%- for post in collections.blog | sortByPubDate | reverse %}
    {%- set absolutePostUrl = post.url | htmlBaseUrl(metadata.base) %}
    <item>
      <title><![CDATA[{{ post.data.title }}]]></title>
      <link>{{ absolutePostUrl }}</link>
      <description><![CDATA[{{ post.data.excerpt }}]]></description>
      <pubDate>{{ post.data.pubdate | dateToRfc822 }}</pubDate>
      <lastBuildDate>{{ post.date | dateToRfc822 }}</lastBuildDate>
      <dc:creator>{{ metadata.author.name }}</dc:creator>
      <guid>{{ absolutePostUrl }}</guid>
      <enclosure url="{{ metadata.base | htmlBaseUrl(metadata.base) }}{{ post.data.image }}" length="{{ post.data.image | getImgSizeInBytes }}" type="image/jpeg" />
    </item>
    {%- endfor %}
  </channel>
</rss>

Here's the (truncated) output:

<?xml version="1.0" encoding="utf-8"?>
<rss version="2.0" xmlns:dc="http://purl.org/dc/elements/1.1/" xml:base="https://my.web.site/" xmlns:atom="https://www.w3.org/2005/Atom">
  <channel>
    <title><![CDATA[My Website]]></title>
    <link>https://my.web.site/</link>
    <atom:link href="https://my.web.site/rss.xml" rel="self" type="application/rss+xml" />
    <description><![CDATA[A description]]></description>
    <language>en-US</language>
    <category>Photography, Blog</category>
    <copyright>Copyright © 2012–2025 Joe Blow. All rights reserved.</copyright>
    <image>
      <url>https://my.web.site/assets/images/site/logo.png</url>
      <title><![CDATA[My Website]]></title>
      <link>https://my.web.site/</link>
      <description><![CDATA[A description]]></description>
      <width>144</width>
      <height>144</height>
    </image>
    <item>
      <title><![CDATA[Side Note Test]]></title>
      <link>https://my.web.site/blog/most-recent-post/</link>
      <description><![CDATA[An excerpt.]]></description>
      <pubDate>Fri, 07 Nov 2025 09:22:08 CST</pubDate>
      <lastBuildDate>Fri, 07 Nov 2025 16:47:09 CST</lastBuildDate>
      <dc:creator>Joe Blow</dc:creator>
      <guid>https://my.web.site/blog/most-recent-post/</guid>
      <enclosure url=?v=cb41ee4bb738"https://my.web.site/assets/images/blog/foo.jpg?v=a7861fa02cfa" length="1362312" type="image/jpeg" />
    </item>
    <item>
      <title><![CDATA[Cat Grass]]></title>
      <link>https://my.web.site/blog/previous-post/</link>
      <description><![CDATA[Another excerpt]]></description>
      <pubDate>Wed, 30 Jul 2025 12:49:53 CDT</pubDate>
      <lastBuildDate>Fri, 07 Nov 2025 14:45:48 CST</lastBuildDate>
      <dc:creator>Joe Blow</dc:creator>
      <guid>https://my.web.site/blog/previous-post/</guid>
      <enclosure url="https://my.web.site/assets/images/blog/bar.jpg?v=6dda186c10ae" length="362015" type="image/jpeg" />
    </item>

[etc.]

  </channel>
</rss>

Note the query string ?v=cb41ee4bb738 in the first <enclosure/>

It looks like the cache-busting strings that 11ty creates for images. But I don't have any idea why it's there; nothing in my code should inseert anything there.

Any help appreciated. URL to the live RSS is https://mercury.photo/rss.xml. View it in Firefox to see the error.

[Ryuno-Ki]

Can you share your Eleventy config? You might have a plugin that adds the parameter.

[seezee]

Sure:

`use strict`;

const browserslist                     = require('browserslist');
const eleventyAutoCacheBuster          = require('eleventy-auto-cache-buster');
const eleventyPluginFilesMinifier      = require('@codestitchofficial/eleventy-plugin-minify');
const esbuild                          = require('esbuild');
const { execSync }                     = require('child_process')
const { feedPlugin }                   = require('@11ty/eleventy-plugin-rss');
const { format }                       = require('date-fns/format');
const { govukEleventyPlugin }          = require('@x-govuk/govuk-eleventy-plugin');
const Image                            = require('@11ty/eleventy-img');
// const { eleventyImageTransformPlugin } = require('@11ty/eleventy-img');
const markdownIt                          = require('markdown-it');
const markdownItAnchor                 = require('markdown-it-anchor');
const markdownItAttrs                  = require('markdown-it-attrs');
const { minify }                       = require('terser');
const outdent                          = require('outdent');
const path                             = require('path');
const pluginSEO                        = require('eleventy-plugin-seo');
// Next 2 constants for JS bundling browser targets
const {resolveToEsbuildTarget}         = require('esbuild-plugin-browserslist');
const target                           = resolveToEsbuildTarget(browserslist(
    'production' [
      '>0.2%',
      'Firefox ESR',
      'not dead',
      'not op_mini all'
    ],
      'development' [
      'last 1 chrome version',
      'last 1 firefox version',
      'last 1 safari version'
    ]
  ), {
  printUnknownTargets: false,
});

const siteURL    = `https://my.web.site`;
const siteAuthor = `Joe Blow`;
const siteName   = `My Website`;
const siteDesc   = `A description`;

// For Markdown attributes
const markdownItOptions = {
  html: true,
  breaks: true,
  linkify: true
};

// Markdown library with options
const markdownLib = (markdownIt) => markdownIt.use(markdownItAttrs).use(markdownItAnchor);

module.exports = async function(eleventyConfig) {

  const {EleventyRenderPlugin} = await import(`@11ty/eleventy`);

  // Enable the markdown-it plugin with options from above
  eleventyConfig.setLibrary(`md`, markdownItOptions);
  // Extend markdown-it via plugins; see https://www.11ty.dev/docs/languages/markdown/#optional-set-your-own-library-instance
  // Most tutorials are written for Eleventy 1.0.0 and use the wrong syntax for v2.0.0 and later
  eleventyConfig.amendLibrary(`md`, markdownLib);

  // Global data
  eleventyConfig.addGlobalData(`siteURL`, {
    "_SITEURL_" : siteURL
  });
  eleventyConfig.addGlobalData(`siteAuthor`, {
    "_AUTHOR_" : siteAuthor
  });
  eleventyConfig.addGlobalData(`siteName`, {
   "_SITENAME_": siteName
  });
  eleventyConfig.addGlobalData(`siteDesc`, {
   "_SITEDESC_": siteDesc
  });
  eleventyConfig.addNunjucksGlobal(`_SITEURL_`, siteURL);
  eleventyConfig.addNunjucksGlobal(`_AUTHOR_`, siteAuthor);
  eleventyConfig.addNunjucksGlobal(`_SITENAME_`, siteName);
  eleventyConfig.addNunjucksGlobal(`_SITEDESC`, siteDesc);

  // Pagefind config; runs AFTER build
  eleventyConfig.on(`eleventy.after`, async function ({ dir }) {
    const inputPath = dir.output;
    const outputPath = path.join(dir.output, `pagefind`);

    console.log(`Creating Pagefind index of %s`, inputPath);

    const pagefind = await import(`pagefind`);
    const { index } = await pagefind.createIndex();
    const { page_count } = await index.addDirectory({ path: inputPath });
    await index.writeFiles({ outputPath });

    console.log(
      `Created Pagefind index of %i pages in %s`,
      page_count,
      outputPath
    );
  });

  // Require layout file extensions; see
  // https://www.11ty.dev/docs/layouts/#omitting-the-layouts-file-extension
  eleventyConfig.setLayoutResolution(false);

  // Copy assets to build directory
  eleventyConfig.addPassthroughCopy(`src/assets/files`);
  eleventyConfig.addPassthroughCopy(`src/assets/fonts`);
  eleventyConfig.addPassthroughCopy(`src/assets/images`);
  eleventyConfig.addPassthroughCopy(`src/assets/media`);

  // Image shortcode
  const imageShortcode = async (
    src,
    className = undefined,
    alt,
    caption,
    widths = [400, 800, 1200, `auto`],
    formats = [`webp`, `jpeg`],
    sizes = `(min-width: 24rem) 90vw, 100vw`
  ) => {

    const imageMetadata = await Image(src, {
      widths: [...widths, null],
      formats: [...formats, null],
      outputDir: `_site/assets/images`,
      urlPath: `/assets/images`,
    });

    /** Maps a config of attribute-value pairs to an HTML string
     * representing those same attribute-value pairs.
     */
    const stringifyAttributes = (attributeMap) => {
      return Object.entries(attributeMap)
        .map(([attribute, value]) => {
          if (typeof value === `undefined`) return ``;
          return `${attribute}="${value}"`;
        })
        .join(` `);
    };

    const sourceHtmlString = Object.values(imageMetadata)
      // Map each format to the source HTML markup
      .map((images) => {
        // The first entry is representative of all the others
        // since they each have the same shape
        const { sourceType } = images[0];

        // Use our util from earlier to make our lives easier
        const sourceAttributes = stringifyAttributes({
          type: sourceType,
          // srcset needs to be a comma-separated attribute
          srcset: images.map((image) => image.srcset).join(`, `),
          sizes
        });

        // Return one <source> per format
        return `<source ${sourceAttributes}>`;
      })
      .join(`\n`);

    const getLargestImage = (format) => {
      const images = imageMetadata[format];
      return images[images.length - 1];
    }

    const largestUnoptimizedImg = getLargestImage(formats[0]);
    const imgAttributes = stringifyAttributes({
      src: largestUnoptimizedImg.url,
      width: largestUnoptimizedImg.width,
      height: largestUnoptimizedImg.height,
      alt,
      loading: `lazy`,
      decoding: `async`,
    });
    const imgHtmlString = `<img ${imgAttributes}>`;

    const pictureAttributes = stringifyAttributes({
      class: className,
    });
    let picture;
    if (caption === undefined) {
      picture = `<picture ${pictureAttributes}>
        ${sourceHtmlString}
        ${imgHtmlString}
      </picture>`;
    } else {
      picture = `<figure><picture ${pictureAttributes}>
        ${sourceHtmlString}
        ${imgHtmlString}
      </picture><figcaption>${caption}</figcaption></figure>`;
    };

    return outdent`${picture}`;
  };

  // SEO
  eleventyConfig.addPlugin(pluginSEO, {
    title: `My Website`,
    description: siteDesc,
    url: siteURL,
    author: siteAuthor,
    twitter: `czahller`,
    options: {
      titleDivider: `|`,
      image: `/assets/images/site/mpb-logo.webp`,
      imageWithBaseUrl: true,
      twitterCardType: `summary_large_image`,
      showPageNumbers: false
    }
  });

  // RSS Feed
	eleventyConfig.addPlugin(feedPlugin, {
    type: `atom`,
		outputPath: `/feed.xml`,
		collection: {
			name: `posts`, // iterate over `collections.posts`
			limit: 0,     // 0 means no limit
		},
    metadata: {
			language: `en-US`,
			title: `My Website`,
			subtitle: `A description`,
			base: siteURL + `/`,
			author: {
				name: siteAuthor
				// email: ``, // Optional
			}
		}
  });

  /**
   * Converts the given date string to ISO8601 format.
   * Example usage: <time datetime="{{ post.date | toISOString | safe}}">
  */
  const toISOString = (dateString) => new Date(dateString).toISOString();
  eleventyConfig.addFilter(`toISOString`, toISOString);
  // Convert length to bytes
  eleventyConfig.addAsyncFilter(`getImgSizeInBytes`, async function (value) {
    const fileImg = await fetch(siteURL + value).then(r => r.blob());

    return fileImg.size;
  });

  // Sort blog entries
  function sortByPubDate(values) {
    let vals = [...values];     // this *seems* to prevent collection mutation...
    return vals.sort((a, b) => Math.sign(a.data.pubdate - b.data.pubdate));
  }

  eleventyConfig.addFilter(`sortByPubDate`, sortByPubDate);

  // Tags index
  eleventyConfig.addFilter(`taglist`, function(collection) {
    const ignoredTags = [`blog`, `all`, `ignore`];
    const tags = [];
    collection.forEach(post => {
        tags.push(...post.data.tags);
    });
    const sorted = [...new Set(tags)]
      .filter((tag) => !ignoredTags.includes(tag))
      .sort((a, b) => a.localeCompare(b));
    return sorted;
  });

  // Needed for paired shortcodes
  eleventyConfig.addPlugin(EleventyRenderPlugin);

  // For inline SVG; see https://medium.com/@brettdewoody/inlining-svgs-in-eleventy-cffb1114e7b
  eleventyConfig.addNunjucksAsyncShortcode(`svgIcon`, async (src) => {
    let metadata = await Image(src, {
      formats: [`svg`],
      dryRun: true,
    })
    return metadata.svg[0].buffer.toString()
  });

  // JS inline minfication
  eleventyConfig.addNunjucksAsyncFilter(`jsmin`, async function (
    code,
    callback
  ) {
    try {
      const minified = await minify(code);
      callback(null, minified.code);
    } catch (err) {
      console.error(`Terser error: `, err);
      // Fail gracefully.
      callback(null, code);
    }
  });

  // Register image shortcode
  eleventyConfig.addNunjucksAsyncShortcode(`image`, imageShortcode);

  // Cache busting
  eleventyConfig.addPlugin(eleventyAutoCacheBuster, {
    globstring: `**/*.{css,js,png,jpg,jpeg,gif,webp,svg,mp4,ico}`
  });

  eleventyConfig.addPlugin(govukEleventyPlugin, {
    markdown: {
      headingPermalinks: true,
    }
  });

  // HTML minification
  eleventyConfig.addPlugin(eleventyPluginFilesMinifier);

  // JS  & CSS bundling, tree-shaking, & minification
  eleventyConfig.on(`eleventy.before`, async () => {
    await esbuild.build({
      entryPoints: [`src/assets/js/index.js`, `src/assets/css/index.css`],
      bundle: true,
      treeShaking: true,
      outdir: `_site/assets/`,
      sourcemap: true,
      minify: true,
      target // From our constant, set at top of file
    });
  });

  // Watch directories for changes
  eleventyConfig.addWatchTarget(`./src/assets/css/`);

  eleventyConfig.addWatchTarget(`./src/assets/js/`);

  // add `date` filter https://date-fns.org/docs/format
  // Usage: {% for item in collections.all %}<lastmod>{{ item.data.lastmod or item.date | date("yyyy-MM-dd'T'hh:mm:ss XXX")}}</lastmod>{% endfor %}
  eleventyConfig.addFilter(`date`, function (date, dateFormat) {
    return format(date, dateFormat)
  })

  eleventyConfig.addPassthroughCopy({
    // Copy files from site root to `_site/` (Don't use backticks around key)
    'favicon': `/`,
    '_redirects': `/`,
    'dislike404-verification.txt': `/`
  });
  // Set custom directory for input; otherwise use defaults
  return {
    // Site URL
    url: siteURL,
    // When a passthrough file is modified, rebuild the pages:
    passthroughFileCopy: true,
    // Copy any file in these formats:
    templateFormats: [`html`, `njk`, `md`, `js`, `woff2`],
    markdownTemplateEngine: `njk`,
    htmlTemplateEngine: `njk`,
    dataTemplateEngine: `njk`,
    // Set up directory structure:
    dir: {
      input: `src`,
    },
  };
};

[Ryuno-Ki]

I suspect https://github.com/Denperidge/eleventy-auto-cache-buster by @Denperidge as the root cause.

[Denperidge]

It does look like its my cache buster! Strange output.

Do RSS feeds benefit from cache busting, or should .rss files be skipped? Depending on that Ill add an RSS exclude, or do some troubleshooting to patch the cache buster behaviour

[seezee]

I can see a case where someone updates a featured image, so the cache busting forces any browser view to use the new image. I have no idea how RSS readers handle cache.

The file format for RSS is actually .xml, so that's what you would target. Maybe add a config option where one can enter the path to the specific file(s) to be excluded?

[seezee]

@Denperidge I added this line to eleventy.js but it didn't help:

globOptions: {nodir: true, ignore: ['rss.xml', 'feed.xml']}

[seezee]

Finally getting somewhere. The query string is coming from the default image. The output should be:

<image>
  <url>https://my.web.site/assets/images/site/logo.png?v=cb41ee4bb738</url>
  [etc.]
</image>
<item>
  [etc.]
  <enclosure url="https://my.web.site/assets/images/blog/foo.jpg?v=408699f46c1a" length="362015" type="image/jpeg" />
  [etc.]
</item>
[etc.]

But instead, it renders:

<image>
  <url>https://my.web.siet/assets/images/site/logo.png</url>
  [etc.]
</image>
<item>
  [etc.]
  <enclosure url?v=cb41ee4bb738="https://my.web.site/assets/images/blog/foo.jpg?v=408699f46c1a" length="362015" type="image/jpeg" />
  [etc.]
</item>
[etc.]

[seezee]

OK, I've figured out what's causing the error (but not why). It's a conflict with @CodeStitchOfficial/eleventy-plugin-minify. I'm exploring other minification via transforms & html-minifier-terser to see if I can get minification to play nicely with caching.

[seezee]

@Denperidge: Switching to html-minifier-terser eliminated the error on rss.xml, but introduced much worse caching conflicts in .html files:

Example output:

<h2 class="admonition-heading">
  <icon-l space=".5em" class="bigger" data-i="Icon-.5em">?v=87bfac47c5e1"About
</h2>
<picture class="img-constrained">
  <source type="image/webp" srcset="/assets/images/eXtAK_R-cP-400.webp 400w, /assets/images/eXtAK_R-cP-768.webp 768w?v=cd74358d3ecd&amp;v=630cb00cde38" sizes="(min-width: 24rem) 90vw, 100vw">
  <source type="image/jpeg" srcset="/assets/images/eXtAK_R-cP-400.jpeg 400w, /assets/images/eXtAK_R-cP-768.jpeg 768w?v=b311772ad383&amp;v=85ad2b1f3793" sizes="(min-width: 24rem) 90vw, 100vw">
  <source type="image/png" srcset="/assets/images/eXtAK_R-cP-400.png 400w, /assets/images/eXtAK_R-cP-768.png 768w?v=94878c72d1cf&amp;v=7a1044fbf3df" sizes="(min-width: 24rem) 90vw, 100vw">
  <img src="/assets/images/eXtAK_R-cP-768.webp" width="768" height="768" alt="?v=cd74358d3ecd&quot;Avatar" depicting="" the="" author.="" he="" is="" wearing="" a="" stingy-brim="" hat="" set="" at="" rakish="" angle.="" his="" pencil-thin="" moustache="" sets="" ladies="" a-swooning."="" loading="lazy" decoding="async">
</picture>

Expected output:

<h2 class="admonition-heading"><icon-l space=".5em" class="bigger" data-i="Icon-.5em">
  About the Author
</h2>
<picture class="img-constrained">
  <source type="image/webp" srcset="/assets/images/eXtAK_R-cP-400.webp 400w, /assets/images/eXtAK_R-cP-768.webp 768w?v=cd74358d3ecd&amp;v=630cb00cde38" sizes="(min-width: 24rem) 90vw, 100vw">
  <source type="image/jpeg" srcset="/assets/images/eXtAK_R-cP-400.jpeg 400w, /assets/images/eXtAK_R-cP-768.jpeg 768w?v=b311772ad383&amp;v=85ad2b1f3793" sizes="(min-width: 24rem) 90vw, 100vw">
  <source type="image/png" srcset="/assets/images/eXtAK_R-cP-400.png 400w, /assets/images/eXtAK_R-cP-768.png 768w?v=94878c72d1cf&amp;v=7a1044fbf3df" sizes="(min-width: 24rem) 90vw, 100vw">
  <img src="/assets/images/eXtAK_R-cP-768.webp?v=cd74358d3ecd" width="768" height="768" alt="Avatar depicting the author. He is wearing a stingy-brim hat set at a rakish angle. His pencil-thin moustache sets the ladies a-swooning." loading="lazy" decoding="async">
</picture>

Here's the configuration:

// Cache busting
eleventyConfig.addPlugin(eleventyAutoCacheBuster, {
  extensions: [`css`, `js`, `png`, `jpg`, `jpeg`, `gif`, `webp`, `svg`, `mp4`, `ico` ]
});

//HTML minification
async function do_minifyhtml(source, output_path) {
  if(!output_path.endsWith(".html") || !is_production) return source;

  const result = await htmlmin(source, {
    collapseBooleanAttributes: true,
    collapseWhitespace: true,
    continueOnParseError: true,
    decodeEntities: true,
    keepClosingSlash: true,
    minifyCSS: true,
    quoteCharacter: `"`,
    removeComments: false,
    removeAttributeQuotes: true,
    removeRedundantAttributes: true,
    removeScriptTypeAttributes: true,
    removeStyleLinkTypeAttributes: true,
    useShortDoctype: false,
    caseSensitive: true
  });

  console.log(`MINIFY ${output_path}`, source.length, `→`, result.length, `(${((1 - (result.length / source.length)) * 100).toFixed(2)}% reduction)`);

  return result;
}

eleventyConfig.addTransform(`htmlmin`, do_minifyhtml);

[Denperidge]

Looks like I should work on tests/compatibility with those minifiers! Which one do you prefer for now? That'll be the first one I work on

(and/or let me know if you would like the ignoreOutputFiles option!)

[seezee]

@Denperidge I'd say @CodeStitchOfficial/eleventy-plugin-minify first. It's a secure fork of @benjaminrancourt/eleventy-plugin-files-minifier (itself abandoned & insecure), tailor-made for Eleventy, and is easier to configure. html-minifier-terser has many more options, which could make troubleshooting complicated, and it causes much worse errors.

AFAIK eleventy-plugin-minify only causes problems on my RSS (.xml) file.

I think the ignoreOutputFiles option would be a nice feature generally, so knock yourself out!

I will spin up a couple of Eleventy instances to reproduce the errors for both and invite you to collaborate once I have them pushed to GitHub (I might not have it done today).

[seezee]

@Denperidge I'm not sure if you saw it, but I've added you as a collaborator on 2 repos.