Practical Tech: Evidence-Backed Self-Hosted Fixes
Reproduced diagnostics for Docker, Cloudflare, and self-hosted stacks. Every guide names the tested environment, rejected shortcuts, safety boundaries, and rollback path. No generic tutorials—only failures we actually fixed.
Docker Diagnostics
Start from the symptom you can reproduce. Isolate the failing layer before applying broad changes.
Bind-mount Permission Denied
A failed/fixed UID/GID lab plus read-only boundary, parent traversal, rootless/userns, SELinux, and rollback checks.
DNS Returns 0.0.0.0
A differential test across host DNS, Docker embedded DNS, AdGuard Home, and an isolated resolver control.
502 from Docker Network Mismatch
A live edge 502, matching cloudflared DNS error, one-network correction, verified 200 response, and rollback evidence.
401: Edge or WordPress?
Same sanitized request at public edge and owned origin. Unauthenticated 401 identical on both paths; valid Application Password yields 200 on both.
Delivery Problems (Legacy Cluster)
Source-checked steps for missing packages, address failures, and carrier escalation. Retained as evidence-backed guides.
Package Says Delivered but It’s Missing?
Check the delivery details and nearby safe locations, then follow the carrier-specific missing-package path. USPS, UPS, and FedEx use different reporting and claim procedures.
Insufficient Address—Can You Fix It Before Return?
What “Insufficient Address” actually means per USPS DMM 507. Recipient vs sender actions, Package Intercept eligibility, Return-to-Sender timeline.
Rental Car Deposit Still Pending After Return?
Authorization hold vs actual charge, Enterprise/Avis/Hertz release timelines, card issuer dispute path, and evidence to collect before escalating.
Rental Car Toll Charge After Return
Separate toll, toll-administrator, convenience-fee, administrative-fee, or citation card charge days or weeks after return. Enterprise/Avis/Alamo/National timing matrix.
Travel & Charges (Legacy Cluster)
Action-first guides for airline name corrections, hotel reservation issues, and baggage fee refunds.
Misspelled Name on Airline Ticket
Display formatting vs legal-name update vs passenger transfer. Ticket issuer, marketing carrier, operating carrier, booking channel separation. American and Delta professional workflows.
Hotel Cannot Find Your Third-Party Reservation
Before travel and at check-in: confirmation chains, virtual credit cards, OTA-to-property sync gaps, walk-in evidence, and escalation order.
Delayed Bag Fee Refund Clock
Domestic 12h / Short-haul 15h / Long-haul 30h. DOT rules, airline-specific claim forms, credit card baggage insurance, and evidence that protects your refund.
Supporting Tools
Browser-local validators for files you prefer not to upload. Explicit capability limits stated.
CSV Import Preflight Validator
Encoding (UTF-8/UTF-16/ISO-8859-1/CP1252), delimiter, required fields, data types, duplicate keys. Presets: Salesforce, HubSpot, Shopify, custom. Downloadable CSV/JSON error report. 100% client-side via PapaParse WASM.
PDF Print Preflight Validator
Inspects MediaBox, CropBox, TrimBox, BleedBox, bleed adequacy (3 mm/0.125 in), rendered page-size comparison. Does not verify: CMYK/spot colors, PPI, font embedding/subsetting, overprint, transparency, PDF/X compliance.
All Validation Tools & Technical Details
Full capability matrix, browser limits, file size guidance, and privacy model for every BigBears zero-upload tool.