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How to implement the first-in, first-out principle in the warehouse data using R

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Summary This postmortem analyzes a warehouse data-processing failure where a FIFO (First‑In, First‑Out) matching algorithm between ship_in_df and ship_out_df produced incorrect or incomplete results. The issue stemmed from an overly simplistic join strategy that ignored inventory depletion order, leading to mismatched cost attribution and inconsistent outbound records. Root Cause The system attempted to match outbound … Read more

Text parsing in PDF

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Summary Text parsing in PDFs often fails due to line-by-line extraction, which disrupts logical grouping of content. This issue arises when parsing libraries like PyMuPDF treat each line as a separate entity, ignoring contextual relationships between lines. Root Cause Line-by-line extraction: PDF parsers often process text line by line, ignoring paragraph or section boundaries. Lack … Read more

Racks questions

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Summary A simulation model in AnyLogic encountered issues with worker assignment and tracking box data in a racking system. Workers needed to be restricted to specific aisles, and box data (weight, volume, and ID) required tracking after storage. Root Cause Worker Assignment: Workers were not properly assigned to specific aisles, leading to inefficiencies. Data Tracking: … Read more

App Store Connect: Xcode Cloud Build Failing with Ad-hoc and Developer Distribution Errors

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Summary This incident involved Xcode Cloud builds failing with Ad‑hoc and Developer Distribution errors (Error code 70) when attempting to upload an iOS app to App Store Connect. The local build and simulator runs succeeded, but the cloud pipeline consistently rejected the archive due to misaligned signing assets and incorrect distribution configuration. Root Cause The … Read more

Timezone Conversion Bug When Scheduling Across Day Boundaries Flutter

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Summary A timezone conversion bug caused scheduling errors when crossing day boundaries, resulting in incorrect execution dates. The issue occurred due to improper handling of date adjustments during timezone conversions, leading to either a one-day delay or repetition of the same day. Root Cause Incorrect date handling: The conversion logic failed to account for day … Read more

UK Met Office migrating from DataPoint to DataHub

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Summary This postmortem examines a common migration pitfall: moving from the Met Office’s legacy DataPoint API to the newer DataHub API and expecting identical data structures. The issue arises when teams assume that symbolic weather codes, descriptive strings, or visibility categories will be preserved across API generations. They are not — and this mismatch leads … Read more

What packages and CLI commands are required to add authentication to an existing ASP.NET Core MVC application?

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Summary Adding authentication to an existing ASP.NET Core MVC application requires specific NuGet packages, .NET CLI commands, and configuration steps. This postmortem outlines the process, root causes of common issues, and best practices for implementation. Root Cause The primary issue arises from missing dependencies and incomplete configuration when integrating ASP.NET Core Identity into an existing … Read more

Why does CPU usage suddenly reach 100% on an AWS EC2 instance running a Next.js application?

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Summary This incident describes a sudden and sustained 100% CPU spike on an AWS t3.micro instance running a Next.js application. After the spike, the Node.js process is killed, often without meaningful logs. This pattern strongly suggests resource exhaustion, runaway background tasks, or event‑loop blocking triggered by recent code changes. Root Cause The most common root … Read more

Question about Postmate Client tool for api testing

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Summary Postmate Client, a VS Code extension for API testing, was evaluated as an alternative to banned tools like Postman and Thunder Client. Initial testing revealed performance bottlenecks and inconsistent request handling, leading to failed API tests and delayed deployments. Root Cause Inefficient request batching: Postmate Client grouped requests in suboptimal batches, causing timeouts. Lack … Read more