Orphan deletion still occurs with empty branchPrefix (regression of #15733) and branchName deprecated (how to replace it with additionalBranchPrefix?) #43674

awrrl · 2026-05-29T09:42:13Z

awrrl
May 29, 2026

How are you running Renovate?

None

Which platform you running Renovate on?

GitHub.com

Which version of Renovate are you using?

v41.159.4

Please tell us more about your question or problem

Context

Our organisation enforces the following branch naming convention via GitHub branch-protection rules:

^(main|\d{3}[\dxX]*)/(develop|renovate-[-\w]+|release|(?:(presc|admin|ddm|pharma|devops|archi)/)?(?:(?:multi-)?feature|bugfix|quality|experiment|buildfix|i18n|patch)(?:/(.+)))|PR-\d+|gh-readonly-queue/.+$

All branches — including Renovate branches — must be prefixed with a version identifier derived from the base branch:

`baseBranch`	Expected Renovate branch
`main/develop`	`main/quality/renovate-maven-artifacts`
`400XXXX/develop`	`400XXXX/quality/renovate-maven-artifacts`

Current configuration (works, but uses deprecated `branchName`)

{
  "$schema": "https://docs.renovatebot.com/renovate-schema.json",
  "baseBranches": ["main/develop", "400XXXX/develop"],
  "branchPrefix": "",
  "additionalBranchPrefix": "",
  "branchName": "{{lookup (split baseBranch '/') 0 }}/quality/renovate-{{{branchTopic}}}"
}

The {{lookup (split baseBranch '/') 0 }} helper extracts the first path segment from baseBranch
(e.g. main from main/develop, 400XXXX from 400XXXX/develop) and uses it as the branch prefix.
This produces the correct branch names at runtime.

However, the documentation for branchName
marks this field as deprecated and recommends using branchPrefix, additionalBranchPrefix, or
branchTopic instead.

Question 1 — How to replace the deprecated `branchName`?

The dynamic prefix needs to go somewhere in the non-deprecated fields.
Does additionalBranchPrefix support the same template variables and helpers as branchName?
The documentation does not make this explicit. Would the following work?

{
  "branchPrefix": "",
  "additionalBranchPrefix": "{{lookup (split baseBranch '/') 0 }}/quality/renovate-"
}

Or is there another recommended approach to achieve a baseBranch-derived prefix?

Question 2 / Bug — Orphan branch deletion with empty `branchPrefix`

Regardless of how the branch name is constructed, setting branchPrefix: "" causes Renovate to
treat every branch in the repository as a Renovate-managed branch. Branches that cannot be
matched to an active update are then marked as orphans and deleted.

We observed this in production (Renovate engine 41.x):

INFO: Deleting orphan branch  branch=main/develop
INFO: Deleting orphan branch  branch=main/multi-feature/HEPIC-12345-split

Relation to the prior fix

This is similar to Discussion #15732,
which was addressed by Issue #15733
and released in v32.83.3.

The isModified check introduced by that fix does provide partial protection: branches with
commits from non-Renovate authors are skipped. However, the fix is incomplete when
branchPrefix is "":

The baseBranch itself is targeted without the isModified check being applied —
when the branch cache is absent, deletion is attempted unconditionally.
"Clean" branches (freshly created, or whose commits Renovate cannot attribute to a
non-Renovate author) remain at risk.
The root cause — every branch name matching the empty prefix, i.e. every branch in
the repository being treated as a Renovate-managed branch — is not addressed.

Minimal reproduction

Confirmed against renovatebot/github-action@v43.0.19 (Renovate engine 41.x):
👉 https://github.com/awrrl/test-renovate-del-orphan

Run 1 — first execution, no prior state:

Renovate correctly created main/quality/renovate-org.apache.commons-commons-lang3-3.x,
then immediately attempted to delete the baseBranch as an orphan (no isModified check
was performed):

DEBUG: setCachedModifiedResult(): Branch cache not present  branch=main/develop
INFO:  Deleting orphan branch                               branch=main/develop
       "commands": ["push", "--delete", "origin", "main/develop", "--no-verify"],
       "message": "refusing to delete the current branch: refs/heads/main/develop"
DEBUG: No remote branch to delete with name: main/develop

The branch was saved only because GitHub refuses to delete the default branch.

Run 2 — warm cache:

Feature branches were also identified as orphans. The isModified check ran and found
commits from non-Renovate authors, so deletion was skipped:

DEBUG: branch.isModified() = true
       "unrecognizedAuthors": ["<non-renovate-author>"]
DEBUG: Orphan Branch is modified - skipping branch deletion  branch=main/feature/EXAMPLE-123
DEBUG: Orphan Branch is modified - skipping branch deletion  branch=main/multi-feature/HEPIC-12345

In our production repositories these same branches were deleted (the branches were clean
with respect to the isModified heuristic), confirming that the isModified check is not a
sufficient safeguard.

Expected behavior

Renovate should identify orphan-branch candidates by matching branch names against the pattern
generated from branchName (or branchPrefix + additionalBranchPrefix + branchTopic).
Branches whose names do not match the generated pattern must never be treated as
Renovate-managed, regardless of whether branchPrefix is empty.

Specifically:

The configured baseBranch must never be a candidate for orphan deletion.
Branches that do not match the branchName template must never be candidates for
orphan deletion.

Logs (if relevant)

Logs

first run ``` 2026-05-29T09:09:21.1175613Z DEBUG: setCachedModifiedResult(): Branch cache not present (repository=awrrl/test-renovate-del-orphan) 2026-05-29T09:09:21.1177021Z INFO: Deleting orphan branch (repository=awrrl/test-renovate-del-orphan, branch=main/develop) 2026-05-29T09:09:22.0510412Z DEBUG: Git function thrown (repository=awrrl/test-renovate-del-orphan) 2026-05-29T09:09:22.0511336Z "err": { 2026-05-29T09:09:22.0511586Z "task": { 2026-05-29T09:09:22.0511990Z "commands": ["push", "--delete", "origin", "main/develop", "--no-verify"], 2026-05-29T09:09:22.0512653Z "format": "utf-8", 2026-05-29T09:09:22.0513146Z "parser": "[function]" 2026-05-29T09:09:22.0513632Z }, 2026-05-29T09:09:22.0515603Z "message": "To https://github.com/awrrl/test-renovate-del-orphan.git\n ! [remote rejected] main/develop (refusing to delete the current branch: refs/heads/main/develop)\nerror: failed to push some refs to 'https://github.com/awrrl/test-renovate-del-orphan.git'\n", 2026-05-29T09:09:22.0522467Z "stack": "Error: To https://**redacted**@3.29.0/node_modules/simple-git/src/lib/plugins/error-detection.plugin.ts:42:29)\n at PluginStore.exec (/usr/local/renovate/node_modules/.pnpm/simple-git@3.29.0/node_modules/simple-git/src/lib/plugins/plugin-store.ts:54:29)\n at /usr/local/renovate/node_modules/.pnpm/simple-git@3.29.0/node_modules/simple-git/src/lib/runners/git-executor-chain.ts:124:42\n at new Promise ()\n at GitExecutorChain.handleTaskData (/usr/local/renovate/node_modules/.pnpm/simple-git@3.29.0/node_modules/simple-git/src/lib/runners/git-executor-chain.ts:121:14)\n at GitExecutorChain.attemptRemoteTask (/usr/local/renovate/node_modules/.pnpm/simple-git@3.29.0/node_modules/simple-git/src/lib/runners/git-executor-chain.ts:97:40)\n at processTicksAndRejections (node:internal/process/task_queues:105:5)\n at GitExecutorChain.attemptTask (/usr/local/renovate/node_modules/.pnpm/simple-git@3.29.0/node_modules/simple-git/src/lib/runners/git-executor-chain.ts:61:18)" 2026-05-29T09:09:22.0527436Z } 2026-05-29T09:09:22.0528129Z DEBUG: No remote branch to delete with name: main/develop (repository=awrrl/test-renovate-del-orphan) 2026-05-29T09:09:22.0576278Z DEBUG: No local branch to delete with name: main/develop (repository=awrrl/test-renovate-del-orphan) ``` second run ``` 2026-05-29T09:16:13.0215855Z DEBUG: Orphan Branch is modified - skipping branch deletion (repository=awrrl/test-renovate-del-orphan, branch=main/feature/EXAMPLE-123) 2026-05-29T09:16:13.0216721Z DEBUG: findPr(main/multi-feature/HEPIC-12345, undefined, open) (repository=awrrl/test-renovate-del-orphan) 2026-05-29T09:16:13.0217426Z DEBUG: branch.isModified(): using git to calculate (repository=awrrl/test-renovate-del-orphan) 2026-05-29T09:16:13.0278952Z DEBUG: branch.isModified() = true (repository=awrrl/test-renovate-del-orphan) 2026-05-29T09:16:13.0280103Z "branchName": "main/multi-feature/HEPIC-12345", 2026-05-29T09:16:13.0280953Z "unrecognizedAuthors": ["Goetz.Lohmann@dedalus.com"] 2026-05-29T09:16:13.0282073Z DEBUG: setCachedModifiedResult(): Branch cache not present (repository=awrrl/test-renovate-del-orphan) 2026-05-29T09:16:13.0283591Z DEBUG: Orphan Branch is modified - skipping branch deletion (repository=awrrl/test-renovate-del-orphan, branch=main/multi-feature/HEPIC-12345) ```

RahulGautamSingh · 2026-06-09T06:58:10Z

RahulGautamSingh
Jun 9, 2026
Collaborator

your suggested config lookks fine and should work, any reason for not putting it in branchPrefix?
Fix PR: fix(prune): skip branch pruning when branchPrefix is empty #43891

2 replies

awrrl Jun 9, 2026
Author

Hi @RahulGautamSingh,

I did try again, and while the field branchPrefix does seem to evaluate the template, the result is not the same.

using

{
  "$schema": "https://docs.renovatebot.com/renovate-schema.json",
  "baseBranches": ["main/develop", "400XXXX/develop"],
  "branchPrefix": "{{lookup (split baseBranch '/') 0 }}/quality/renovate-{{{branchTopic}}}"
}

or

{
  "$schema": "https://docs.renovatebot.com/renovate-schema.json",
  "baseBranches": ["main/develop", "400XXXX/develop"],
  "branchPrefix": "",
  "additionalBranchPrefix": "{{lookup (split baseBranch '/') 0 }}/quality/renovate-{{{branchTopic}}}"
}

will create branches like:
main/develop-main/quality/renovate-branch-topic
400XXXX/develop-400XXXX/quality/renovate-branch-topic
(see the double take)

instead of

{
  "$schema": "https://docs.renovatebot.com/renovate-schema.json",
  "baseBranches": ["main/develop", "400XXXX/develop"],
  "branchPrefix": "",
  "additionalBranchPrefix": "",
  "branchName": "{{lookup (split baseBranch '/') 0 }}/quality/renovate-{{{branchTopic}}}"
}

which result in branches created as:
main/quality/renovate-branch-topic
400XXXX/quality/renovate-branch-topic

awrrl Jun 9, 2026
Author

I tried to apply this in a dedicated repo: fix-renovate-del-orphan, which partially worked till I added an additional branch and the configuration merge.

I fear this branch naming issue stem in fact from the use of "useBaseBranchConfig": "merge", to ensure that ranges for lower versions are correctly applied and also behaviours are updated (auto merge on main/develop but not for children).
Unfortunatley, it seems the merge is not only applying to the rules but also to the branch naming :/

awrrl · 2026-06-09T08:53:57Z

awrrl
Jun 9, 2026
Author

Hi @RahulGautamSingh,

thanks for your feedback and yes, we indeed tried using the template syntax in the field branchPrefix first, but it didn't resolve the template and the last time I checked did not have the indicator This option supports Renovate's template syntax, but does say:

branchPrefix must be configured at the root of the configuration (e.g. not within any package rule) and is not allowed to use template values. e.g. instead of renovate/{{parentDir}}-, configure the template part in additionalBranchPrefix, like "additionalBranchPrefix": "{{parentDir}}-".

So you probably want to amend that section in the document to match the new info. I will certainly try again and if this works with branchPrefix, I will be happy to use this and report back (and mark your post as answered).

kind regards,
Götz

1 reply

RahulGautamSingh Jun 19, 2026
Collaborator

Sure thing. I will debug locally to see why it's not working, my knowledge on it os a bit rusty at the moment.

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Orphan deletion still occurs with empty branchPrefix (regression of #15733) and branchName deprecated (how to replace it with additionalBranchPrefix?) #43674

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Orphan deletion still occurs with empty branchPrefix (regression of #15733) and branchName deprecated (how to replace it with additionalBranchPrefix?) #43674

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awrrl May 29, 2026

How are you running Renovate?

Which platform you running Renovate on?

Which version of Renovate are you using?

Please tell us more about your question or problem

Context

Current configuration (works, but uses deprecated branchName)

Question 1 — How to replace the deprecated branchName?

Question 2 / Bug — Orphan branch deletion with empty branchPrefix

Relation to the prior fix

Minimal reproduction

Expected behavior

Logs (if relevant)

Replies: 2 comments · 3 replies

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RahulGautamSingh Jun 9, 2026 Collaborator

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awrrl Jun 9, 2026 Author

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awrrl Jun 9, 2026 Author

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awrrl Jun 9, 2026 Author

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RahulGautamSingh Jun 19, 2026 Collaborator

awrrl
May 29, 2026

Current configuration (works, but uses deprecated `branchName`)

Question 1 — How to replace the deprecated `branchName`?

Question 2 / Bug — Orphan branch deletion with empty `branchPrefix`

Replies: 2 comments 3 replies

RahulGautamSingh
Jun 9, 2026
Collaborator

awrrl Jun 9, 2026
Author

awrrl Jun 9, 2026
Author

awrrl
Jun 9, 2026
Author

RahulGautamSingh Jun 19, 2026
Collaborator