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Error parsing Custom CSS, verify Custom CSS is valid

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When I went to add a post to my blog I got the following error message: Error parsing Custom CSS, verify Custom CSS is valid.

So I went into Design > Custom CSS where I found the code pasted below. I think I put this code in there to prevent people from right clicking. It was to protect my images, but obviously something has changed and it is now giving an error message.

At the bottom of the code block it said they error was in the syntax in line 1.

I am using the Avenue template.

I'd really appreciate some help if anyone knows how I can fix it.




<SCRIPT language=JavaScript>
   var message = "function disabled"; 
   function rtclickcheck(keyp){ if (navigator.appName == "Netscape" && keyp.which == 3){   alert(message); return false; } 
   if (navigator.appVersion.indexOf("MSIE") != -1 && event.button == 2) {  alert(message);     return false; } } 
   document.onmousedown = rtclickcheck;

Edited by Secret_Brisbane
New information
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I am also receiving this error message on my event items when I go to edit the details of an event button. The formatting does not appear correctly while I am editing in the details window but it is appearing correctly when I view it on the web or via mobile. I haven't made any changes to the CSS in months and am not sure why this is popping up now. 

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Hey everyone, 

Did anyone get an answer to this? I'm seeing the same on all blog posts in 3 different sections of my website. 

No syntax errors in the CSS at all, so I completely removed all the CSS and the same issue occurs 'Error parsing Custom CSS, verify Custom CSS is valid' . I'm guessing this is potentially a Squarespace issue, as creedon has said. 

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On 11/19/2022 at 10:42 AM, creedon said:

I can't say for sure but this sounds like it might be an issue with SS's backend. There is nothing we can do to fix a backend issue. You'd need to contact Contact Customer Support.


On 11/18/2022 at 6:37 PM, Mila__osman said:

I'm also having this issue. I removed the custom css code entirely and STILL can't post to my blog and get the same error code. I am on Brine 7.0.

I am also on Brine 7.0. For the record, one of my clients is on SS 7.1 and I am not getting the same error message on their website.

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Having a related issue when going to update currently published events on my website's calendar (I'm guessing because this is actually a blog) and when trying to edit a draft event duplicated from any existing event.

We're also on 7.0, but with Bedford family (Bryant Hill template).

Edited by gwen
corrected template type
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On 11/19/2022 at 7:55 PM, Secret_Brisbane said:

Thank you @creedon. I've deleted the code completely from the Custom CSS, then I logged out and closed the page and then went back in. Same thing: I am still getting the error message.

Have you tried clearing your cache? Squarespace suggested that this was only happening to a small number of users and gave that to me as a solution (which did not work). 

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2 hours ago, Bushlore said:

I found a work around, expand the text box by clicking the arrow in the right hand corner. Once expanded I can add text and images and it removes the error. Works for me on event and blog posts.

That didn't help in my instance — the editor in that view was still treating my entire event/blog post like a single code block, and only bringing up one small code block we have for an integrated checkout to edit when I tried to edit things.

There was an error in our site CSS that we fixed (thanks, Saga from Squarespace!) and then Squarespace had to clear a cache for the error to disappear in our case. I also had to clear my browser cache again for the fix to show up on my end.

Hoping this helps anyone else looking for a solution — I think if you don't have any custom CSS folks will need to contact customer support and ask for assistance and make sure to ask them to clear the site cache.

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Reported to Squarespace and had the following response. Any thoughts really welcomed as I can’t see any visible errors in the site itself, just in the back end. Even removed Custom CSS and error continues. 

To provide a bit more context, we were seeing an elevated rate of custom CSS errors interfering with editing tools. To help flag this, we released the 'CSS parsing error' banner as a new editor 'feature' this week.
In this case, the 'CSS parsing error' banner is displaying due to formatting issues in the Custom CSS panel and the util.less file. 
Updates to the platform can cause a site's custom code to behave differently or break. This means custom code can interfere with your site's behavior or stop working at any time, even if it previously worked or wasn't interfering.
Because of this, we can't ensure that any custom code will be compatible with the platform. To learn more, visit our guide:

Edited by Icclebug
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I also got response from Squarespace but I just find that they are shirking responsibility and effort to rectify this. The way they handle this issue is not customer oriented at all and created much inconveniences for all of us. Moreover the customer service is telling me if i do not want to edit the custom code myself i will hire an independent designer to do it which is extra costs and dangers of messing up the entire code having known that most of us are self owned businesses managing sites on our own. 

So with every platform update are there going to be new 'feature' issues created for us? Did we pay for such troubles given they have raised their pricing fees this year?

Reply quote: "I can confirm that the CSS parsing error message that you see in the pop-up editor is due to a platform update on our end. "

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14 minutes ago, Lim said:

So with every platform update are there going to be new 'feature' issues created for us?

SS is upfront about using custom code. They don't support it. So if you use it then it is on you to maintain it. That means that at some point your custom code will break as SS is not a static platform.

Folks in the world of computing, as in all things, there is no such thing as a forever static unchanging platform. All things change.

Find my contributions useful? Please like, upvote, mark my answer as best , and see my profile. Thanks for your support!

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