Lighthouse "Not_HTML" error after installing Lazify

1 0 0

Hello everyone,


As we are working on our addressing site speed with Lighthouse, we installed an App called "Lazify" with the goal of lazy loading our images. 


After the app was installed we received the error:  "Lighthouse returned error: NOT_HTML.  The page provided is not HTML.  (served as MME type text/plain)."

Screen Shot 2021-11-11 at 10.44.57 AM.png

We have now removed the app, and this error is persisting.   Can anyone suggest any fixes for this issue?

Replies 6 (6)

Not applicable

Hi @TeamZeacon 

Aibek is here from agency. 

It's difficult to say with this provided data. 

Can you please share the URL of your shop, so we can check?


Also, we have launched our app: 

That helps to increase Page Speed metrics and have faster store without code knowledge.


65 6 28

We're also seeing issues with "NOT_HTML" on our site the past days - see e.g. this link. If any suggestions, we would be very interested.

4 0 1

its not due to any app there are few updates from pageSpeed Insight after that almost all shopify store are getting same error 

3 0 2

I am getting the same error and thought it was because I had downloaded an SEO optimizer app.  So most if not all Shopify stores are experiencing the same thing?

Shopify Partner
244 29 129

Yes, from answers on stack overflow, it seems the issue is caused by Lighthouse not recieving the the mime type they expected. In the case of Shopify, maybe Shopify is sending some early server hint that is confusing the new configuration for PSI and that causes the error.
Might take a month to fix, taking into account the speed of the update history for PSI.

Available for freelance. I specialize in speed improvement and theme development.

You can also contact me directly if you prefer.

4 0 1

Boa tarde, segundo as últimas atualizações me passaram que não está relacionado a nenhum app. Podem ficar tranquilos! Relatei ontem pelo twitter ao shopify o mesmo problema e me deram a resposta final que seus desenvolvedores vão atrás da solução para o problema. Obrigado a todos que relatam pelo fórum, pois só assim um problema tão grave quanto este pode ser solucionado agora muito mais rápido! Nosso site Pakinha Adesivos do Brasil.