{"record":{"id":"8691e00891d38451","repo":"Billionmail/BillionMail","slug":"unable-to-get-captcha-after-multiple-attempts","errorCode":null,"errorMessage":"unable to get captcha after multiple attempts","messagePattern":"unable to get captcha after multiple attempts","errorType":"error_code","errorClass":null,"httpStatus":null,"severity":"error","filePath":"core/internal/service/rbac/validate_code.go","lineNumber":219,"sourceCode":"\n\t\t\t// Asynchronously refresh if pool size is below threshold\n\t\t\tif poolSize < p.refreshRate {\n\t\t\t\tgo p.RefreshPool(false)\n\t\t\t}\n\n\t\t\treturn captchaID, b64s, nil\n\t\t}\n\n\t\tp.mutex.Unlock() // Ensure unlock\n\t}\n\n\t// Final attempt to generate a captcha directly as fallback\n\tid, b64s, _, err = p.captcha.Generate()\n\tif err == nil {\n\t\treturn id, b64s, nil\n\t}\n\n\treturn \"\", \"\", errors.New(\"unable to get captcha after multiple attempts\")\n}\n\n// VerifyCode Verify captcha\nfunc (p *CodePool) VerifyCode(id, answer string) bool {\n\treturn p.store.Verify(id, answer, true)\n}\n\n// GetAnswer Get captcha answer (without consuming the captcha)\nfunc (p *CodePool) GetAnswer(id string) string {\n\treturn p.store.Get(id, false)\n}\n\n// GenerateCaptcha Generate a single captcha\nfunc GenerateCaptcha() (id string, b64s string, answer string, err error) {\n\treturn GetCodePool().captcha.Generate()\n}\n\n// GetCaptcha Get a captcha from the captcha pool","sourceCodeStart":201,"sourceCodeEnd":237,"githubUrl":"https://github.com/Billionmail/BillionMail/blob/fc36c76c050c3775c5e899faf7403cf0262d2744/core/internal/service/rbac/validate_code.go#L201-L237","documentation":"GetCode pulls a captcha from a pre-filled pool, refills it if needed, and as a last resort generates one directly. Only if every path — pool, refill, and direct generation — fails does it return 'unable to get captcha after multiple attempts'. Generation depends on an image backend (font/graphics library), so failures usually stem from that subsystem.","triggerScenarios":"All three attempts fail: pool empty, refill generation errors, and the direct p.captcha.Generate() fallback also returns an error — commonly when the image/font library can't render (missing fonts, image lib not available) or the generator is out of memory.","commonSituations":"Container images missing font packages required by go-captcha/freetype; repeated rapid calls exhausting the pool faster than refill; resource limits on small deployments.","solutions":["Check the underlying Generate error — inspect pool/generator logs for the real cause (fonts, image library).","Install required font packages in the container (e.g. fontconfig/freetype fonts).","Verify the captcha library's image backend is supported in your base image (add graphics deps).","Increase pool size/refill rate if load exhausts the pre-filled pool.","Have callers return HTTP 503 and let the client retry the captcha request."],"exampleFix":null,"handlingStrategy":"retry","validationCode":"// ensure fonts/graphics deps exist at container start\nif _, err := os.Stat(\"/usr/share/fonts\"); err != nil {\n    log.Fatal(\"font packages missing: captcha rendering unavailable\")\n}","typeGuard":null,"tryCatchPattern":"id, b64s, err := service.GetCode(ctx)\nif err != nil {\n    if strings.Contains(err.Error(), \"unable to get captcha after multiple attempts\") {\n        return ghttp.Res503(\"captcha temporarily unavailable, retry\")\n    }\n    return err\n}","preventionTips":["Bake required font packages into the container image.","Size the captcha pool above peak request rate and monitor refill latency.","Alert on any Generate errors before the final fallback fires.","Return 503 + Retry-After to clients so they re-request rather than hang."],"tags":["captcha","retry","pool"],"backgroundTag":"captcha-generation-failed","analyzedSha":"fc36c76c050c3775c5e899faf7403cf0262d2744","analyzedAt":"2026-09-05T21:28:54.019Z","contentChangedAt":"2026-09-05T21:28:54.019Z","schemaVersion":2},"datasetVersion":"2026-09-12T22:17:10.623Z"}