CM360 Ad Ops · 8 min read · Verified 2026

Campaign Manager 360 HTML5 Creative Upload Troubleshooting

Google Campaign Manager 360 (formerly DoubleClick CM) is the enterprise ad serving standard for US agencies. However, uploading HTML5 display creatives to CM360 frequently results in confusing rejection codes.

Top 4 CM360 Upload Errors & Fixes

1. "Primary Asset index.html is Missing"

Cause: The ZIP archive was compressed by zipping a parent folder rather than selecting the files directly. CM360 expects index.html at the root level of the ZIP file.

Fix: Select index.html and all asset folders directly, right-click, and choose Compress / Send to ZIP.

2. "ClickTag variable not found"

Cause: Syntax error or non-standard variable name. CM360 requires exact case-sensitive JavaScript variable declaration inside the HTML <head>.

<script type="text/javascript">
  var clickTag = "https://www.example.com";
</script>

3. "File size exceeds 150 KB limit"

Cause: Uncompressed high-resolution PNGs or unminified JS libraries included in the ZIP bundle.

Fix: Convert PNGs to WebP/optimized JPEG or load Google-hosted JS libraries (GSAP, CreateJS) via external CDN.

Test your ZIP files against CM360 upload rules instantly with our HTML5 Banner Validator.