What causes "Hashtag cannot be empty" in gitbutlerapp/gitbutler?

Remove the empty --hashtag argument

Hashtag cannot be empty

Error message

Hashtag cannot be empty

What it means

With gerrit mode enabled, each `--hashtag` value is trimmed and must be non-empty before it becomes `but_gerrit::PushFlag::Hashtag`. Empty or whitespace-only input is rejected because a Gerrit hashtag is review metadata and cannot be blank.

Source

Thrown at crates/but/src/command/legacy/push.rs:1075

    if !gerrit_mode {
        return Ok(vec![]);
    }

    let mut flags = Vec::new();

    // Handle Wip/Ready - Ready is default if neither is specified
    if args.wip {
        flags.push(but_gerrit::PushFlag::Wip);
    } else {
        // Default to Ready, or explicit Ready
        flags.push(but_gerrit::PushFlag::Ready);
    }

    // Handle hashtags - can be multiple
    for hashtag in &args.hashtag {
        if hashtag.trim().is_empty() {
            return Err(anyhow::anyhow!("Hashtag cannot be empty"));
        }
        flags.push(but_gerrit::PushFlag::Hashtag(hashtag.clone()));
    }

    // Handle topic - at most one
    if let Some(topic) = &args.topic {
        if topic.trim().is_empty() {
            return Err(anyhow::anyhow!("Topic cannot be empty"));
        }
        flags.push(but_gerrit::PushFlag::Topic(topic.clone()));
    } else if args.topic_from_branch {
        flags.push(but_gerrit::PushFlag::Topic(branch_name.to_string()));
    }

    // Handle private flag
    if args.private {
        flags.push(but_gerrit::PushFlag::Private);
    }

View on GitHub (pinned to caf1f223d3)

Solutions

Remove the empty --hashtag argument
Give the hashtag a real value: `but push --hashtag my-team`
Guard scripts to skip empty values when building the flag list

Example fix

# before
but push --hashtag ""
# error: Hashtag cannot be empty

# after
but push --hashtag my-team

Defensive patterns

Strategy: validation

Validate before calling

# Drop empty/blank hashtags before invoking but
args=()
for tag in "${hashtags[@]}"; do
  [ -n "${tag//[[:space:]]/}" ] && args+=(--hashtag "$tag")
done
but push "${args[@]}"

Prevention

Validate list-valued flags in wrappers before exec
Quote CI variables so empty ones are visible instead of silently forwarded
Fail fast on blank inputs rather than passing them through

When it happens

Trigger: Running `but push --hashtag ""` or `--hashtag " "` in a Gerrit-enabled repo; a shell loop expanding an empty variable into the flag.

Common situations: CI variable left empty and passed through a loop; copy-paste leaving a placeholder value; accidental empty element in a flag list.

Related errors

AI-assisted analysis of gitbutlerapp/gitbutler@caf1f223d3 (2026-08-20). Data as JSON: /api/errors/44b9049776cf322a. Report an issue: GitHub.