Blog Sections Open
Fixing “Cannot modify header information” Errors After Installing EvoGallery
Header warnings usually mean one thing: something started sending output before the manager finished the response.
A real-world case described a Cannot modify header information warning that appeared after installing EvoGallery on an older Evolution build. The message pointed at the document parser and the save processor, which is typical for this class of issue: the real problem is earlier output.
What usually causes it
- an included file echoes something too early
- a plugin or module triggers warnings before headers are sent
- debug output, whitespace, or notices leak into the response
Why gallery packages can trigger it
Media-oriented extras often touch manager rendering, file handling, and output-heavy code paths. On older Evo builds, a small warning or stray output becomes enough to break header operations during save actions.
How to debug it
Do not start with the final header warning line. Start with the earliest output source: notices, warnings, BOM issues, or unexpected text emitted before the manager processor finishes.
Fixing tagManager AJAX Pagination That Falls Back to 404 Pages
Why tagManager filtering with AJAX can start returning 404s on paginated URLs and how to keep state, routing, and pagination aligned.
Enabling Browser Caching with .htaccess in Evolution CMS
A practical performance note on using Expires headers in .htaccess to improve browser caching for CSS, JavaScript, images, and other static assets.