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Troubleshooting Common OMGF Plugin Issues: Speed, Preload, and MIME Type Errors

17 threads Sep 9, 2025

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OMGF | GDPR/DSGVO Compliant, Faster Google Fonts. Easy. is a popular tool for self-hosting Google Fonts, but like any plugin, users can sometimes encounter issues. This guide addresses the most common problems reported by the community and provides steps to resolve them.

1. No Noticeable Performance Improvement

Problem: After installing OMGF, some users report no improvement in page load times or page weight.

Why It Happens: OMGF's primary performance gain comes from serving fonts locally, which reduces the time spent on external DNS lookups and connections. However, if another factor is the main bottleneck on your site (e.g., unoptimized images, slow hosting, or other render-blocking resources), the improvement from local fonts may be overshadowed.

Solution: Use a tool like GTmetrix or Pagespeed Insights to perform a full audit of your site. Look for larger issues than fonts, such as 'Reduce Initial Server Response Time' or 'Properly Size Images.' Addressing these may reveal the performance gains from OMGF.

2. Preload Warnings in Google Pagespeed Insights

Problem: Google Pagespeed Insights suggests preloading key font requests even after OMGF is active.

Why It Happens: This is a suggestion for further optimization, not necessarily an error. OMGF moves the fonts to a local source, but browsers may still discover them later in the loading process.

Solution: OMGF includes an experimental 'Enable preload for stylesheet' option in its settings. Enabling this can instruct the browser to prioritize loading the font files. Be aware that incorrect use of preload can sometimes harm performance, so test your site's speed after enabling it.

3. "Refused to apply style" MIME Type Error

Problem: Browser consoles show an error: Refused to apply style from... because its MIME type (‘text/html’) is not a supported stylesheet MIME type.

Why It Happens: This error indicates the browser requested the OMGF-generated stylesheet (fonts.css), but the server returned a text/html response (like a 404 error page) instead of a text/css file. This is often a temporary server or caching issue.

Solution: This problem often resolves itself. First, try these steps:

  • Clear all caching on your site (including any caching plugins, server-level cache, and CDN caches).
  • Use the 'Empty Cache Directory' button in OMGF's settings to force the plugin to regenerate its files.
  • Open your site in a fresh incognito/private browser window to check if the error is gone.

4. Plugin Not Working With a Child Theme

Problem: OMGF works with the parent theme but stops processing fonts when a child theme is activated.

Why It Happens: A common reason is that the parent theme loads fonts via @import rules in its CSS file. The free version of OMGF cannot process fonts loaded this way; this functionality is reserved for the Pro version.

Solution: Check how your parent theme loads Google Fonts. If it uses @import statements in its CSS, the free version of OMGF will not be able to detect and optimize them.

5. Leftover Data After Uninstalling the Plugin

Problem: Database entries or files remain after uninstalling OMGF.

Why It Happens: Older versions of the plugin did not always clean up all data upon uninstallation.

Solution: To ensure complete removal:

  1. Reinstall the OMGF plugin.
  2. Navigate to OMGF > Advanced Settings.
  3. Check the box for Remove Settings/Files at Uninstall.
  4. Deactivate and delete the plugin again through the WordPress admin panel.
This will trigger a clean uninstallation routine that removes all traces of the plugin.

By understanding these common issues, you can more effectively troubleshoot and get the most out of the OMGF plugin on your WordPress site.

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