Your antivirus browser extension is likely the cause — not a problem with your account.
Learning Clarity Team · Updated
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If the payment page goes blank, spins forever, or throws errors — this article explains why and how to fix it in 30 seconds.
What's Happening
Stripe's checkout page enforces a strict Content Security Policy (CSP) — it only allows its own trusted scripts and styles to run.
Browser extensions from antivirus tools — such as Kaspersky, Avast, Norton, and similar products — inject their own scripts and styles into every page you visit, including Stripe's checkout. Stripe's CSP rightfully blocks these injections, and in the process, Stripe's own scripts can also fail to load.
Common Symptoms
The checkout page goes blank or never finishes loading
A spinning loader that never resolves
Console errors mentioning MIME type mismatches, CSP violations, or CORS failures
Error codes like 499 on Stripe's JS bundles
How to Fix It
1Option 1 — Disable the antivirus browser extension (recommended)
In your browser's extensions menu, temporarily disable Kaspersky Internet Security, Avast Online Security, Norton Safe Web, or whichever antivirus extension is installed. Then reload the page and try checkout again. You can re-enable the extension once your purchase is complete.
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Many antivirus extensions have a per-site whitelist. You can whitelist checkout.stripe.com so only that domain is unprotected, instead of disabling the extension entirely.
2Option 2 — Use a private / incognito window
Open a new incognito window (Chrome: Ctrl+Shift+N / Cmd+Shift+N) or private window (Firefox: Ctrl+Shift+P). Browser extensions are typically disabled in private mode by default. Navigate to the app and retry your purchase.
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This is not a bug in Learning Clarity or a problem with your account. Your credits and payment history are safe. The issue is entirely between Stripe's security policies and your browser extension.
Frequently Asked Questions
Was I charged if the checkout page never loaded?›
No. If Stripe’s page never finished loading, no payment was taken and no credits were deducted. Your credit balance and payment history are untouched.
Do I have to turn my antivirus off completely?›
No. Disable only its browser extension, or better, whitelist checkout.stripe.com in that extension’s per-site settings so nothing else changes. Either way you can re-enable it as soon as the purchase is done.
Checkout worked in a private window. Is something wrong with my normal browser?›
No. Private windows disable extensions by default, which is exactly why it worked — it confirms an extension is injecting scripts that Stripe’s content security policy blocks.