Problem sharing deck on AnkiWeb

I’m having the exact same problem now. Last update was a month ago, went smoothly - I haven’t added anything new since. This is the deck in question : Raagaception's 12STD CBSE Deck (Science stream, PCM) - AnkiWeb

Deleted all Note types except my custom Basic and Cloze note types. Checked database, deleted unused media. Any idea on what might have gone wrong?

EDIT : the update I’m trying to do involves modifying the tags, I haven’t added any new cards. Is having new cards in the update compulsory?

Your notetype is referencing a field that doesn’t exist, so you should remove the following lines:

{{#FrontOpt}}
<div class="frontopt">{{FrontOpt}}</div>
{{/FrontOpt}}

@Rumo when wrapped in a conditional, no warning appears, so it looks as if the card is fine when it’s not. Perhaps we could could do something like the following?

diff --git a/rslib/src/template.rs b/rslib/src/template.rs
index 1bde79f3d..d067b8798 100644
--- a/rslib/src/template.rs
+++ b/rslib/src/template.rs
@@ -469,6 +469,12 @@ fn render_into(
             Conditional { key, children } => {
                 if context.nonempty_fields.contains(key.as_str()) {
                     render_into(rendered_nodes, children.as_ref(), context, tr)?;
+                } else if !context.fields.contains_key(key.as_str()) && !card_ordinal_reference(key)
+                {
+                    return Err(TemplateError::ConditionalNotFound {
+                        field: key.to_string(),
+                        prefix: "#",
+                    });
                 }
             }
             NegatedConditional { key, children } => {

We’d need to exclude references like {{#c3}}

I haven’t worked directly with this code, but it sounds reasonable.

Oh damn, my bad. Thanks for the heads up!
I’ll make the note type correction for a major deck update (when I make it after a few exams) and let you know if it worked - can’t update casually right now as it might confuse the deck users.