{"record":{"id":"75589ae818299f0b","repo":"mermaid-js/mermaid","slug":"trying-to-create-an-existing-branch-help-either","errorCode":null,"errorMessage":"Trying to create an existing branch. (Help: Either use a new name if you want create a new branch or try using \"checkout ${name}\")","messagePattern":"Trying to create an existing branch\\. \\(Help: Either use a new name if you want create a new branch or try using \"checkout (.+?)\"\\)","errorType":"exception","errorClass":"Error","httpStatus":null,"severity":"error","filePath":"packages/mermaid/src/diagrams/git/gitGraphAst.ts","lineNumber":141,"sourceCode":"    parents: state.records.head == null ? [] : [state.records.head.id],\n    branch: state.records.currBranch,\n  };\n  state.records.head = newCommit;\n  log.info('main branch', config.mainBranchName);\n  if (state.records.commits.has(newCommit.id)) {\n    log.warn(`Commit ID ${newCommit.id} already exists`);\n  }\n  state.records.commits.set(newCommit.id, newCommit);\n  state.records.branches.set(state.records.currBranch, newCommit.id);\n  log.debug('in pushCommit ' + newCommit.id);\n};\n\nexport const branch = function (branchDB: BranchDB) {\n  let name = branchDB.name;\n  const order = branchDB.order;\n  name = common.sanitizeText(name, getConfig());\n  if (state.records.branches.has(name)) {\n    throw new Error(\n      `Trying to create an existing branch. (Help: Either use a new name if you want create a new branch or try using \"checkout ${name}\")`\n    );\n  }\n\n  state.records.branches.set(name, state.records.head != null ? state.records.head.id : null);\n  state.records.branchConfig.set(name, { name, order });\n  checkout(name);\n  log.debug('in createBranch');\n};\n\nexport const merge = (mergeDB: MergeDB): void => {\n  let otherBranch = mergeDB.branch;\n  let customId = mergeDB.id;\n  const overrideType = mergeDB.type;\n  const customTags = mergeDB.tags;\n  const config = getConfig();\n  otherBranch = common.sanitizeText(otherBranch, config);\n  if (customId) {","sourceCodeStart":123,"sourceCodeEnd":159,"githubUrl":"https://github.com/mermaid-js/mermaid/blob/d93e9c88c01a599c062ee6a3f1462e3558ac6b90/packages/mermaid/src/diagrams/git/gitGraphAst.ts#L123-L159","documentation":"Error \"Trying to create an existing branch. (Help: Either use a new name if you want create a new branch or try using \"checkout ${name}\")\" thrown in mermaid-js/mermaid.","triggerScenarios":"Thrown at packages/mermaid/src/diagrams/git/gitGraphAst.ts:141 when the library encounters an invalid state.","commonSituations":"See trigger scenarios.","solutions":[],"exampleFix":null,"handlingStrategy":null,"validationCode":null,"typeGuard":null,"tryCatchPattern":null,"preventionTips":[],"tags":[],"backgroundTag":null,"analyzedSha":"d93e9c88c01a599c062ee6a3f1462e3558ac6b90","analyzedAt":"2026-08-12T06:23:11.304Z","schemaVersion":2},"datasetVersion":"2026-08-12T13:17:24.610Z"}