LMDB nested RW transaction

Summary The core issue was a failure to correctly handle a parent transaction handle lifecycle. The user attempted to nest a read-write transaction (wtxn) inside a parent transaction that was either read-only (th was RO) or a handle passed from an external scope (th existed). The mdb_txn_begin call failed with EINVAL because the parent argument … Read more

How can i run my code in c in html with apache2 server

Summary This postmortem analyzes the architectural mismatch between a user’s request to execute C programs on-demand via Apache and the security/operational realities of web server design. The core confusion lies in treating a web server as an interactive shell rather than a restricted service gateway. We identify the root causes as a misunderstanding of the … Read more

SpringBoot project/dependencies and versions problems

Summary The project fails to compile with a Toolchain Mismatch error (java.lang.ExceptionInInitializerError com.sun.tools.javac.code.TypeTag :: UNKNOWN). This error occurs because the build environment is using an incompatible JDK version relative to the Spring Boot and Maven Compiler configurations. Specifically, while the project targets Java 21, the active JDK running the Maven build is likely an older … Read more

Bitcoin Stratum shares rejected despite successful submission — MacMetal Miner on Apple Silicon

Summary A Bitcoin miner on Apple Silicon using the Metal framework was submitting shares that the pool rejected with a diff mismatch or low difficulty error, despite the local log showing a difficulty of 38. The root cause was a difficulty target mismatch: the miner was correctly hashing at the pool-assigned difficulty, but the pool’s … Read more

Dependencies using conanfile.py

Summary When integrating Boost, Boost.Asio, and a local library with custom include paths into a project using Conan, the core requirement is to correctly define local source paths in the conanfile.py alongside remote package dependencies. The mistake often lies in treating local libraries as Conan packages prematurely or failing to expose custom include directories to … Read more

Android clipboard not providing previously copied MIME-type when trying to retrieve data from it

Summary The Android clipboard system is designed for universal interoperability across applications. When an application copies custom data, the system may not preserve the original MIME-type you specified, defaulting instead to text/plain. This is not a bug; it is a known system-level behavior that affects custom MIME-type retrieval. In your specific case, the issue stems … Read more

Pico 2W MbedTLS LwIP Crt verification fails on Supabase POST

Summary A developer using a Raspberry Pi Pico 2W with MbedTLS and LwIP encountered certificate verification failures when connecting to a Supabase backend, while connections to other APIs functioned correctly. The specific error indicated an expired certificate despite the system time being correctly synchronized via SNTP. The issue was identified as failed certificate chain validation … Read more

Undefined symbol in Visual Studio 2022 clang-cl

Summary A build failed with lld-link reporting undefined symbols when compiling an Intel Pin tool with clang-cl in Visual Studio 2022. The linker could not resolve essential Pin API functions like IMG_Name and IMG_LowAddress, despite linking against pin.lib. The root cause was a mismatch between the C++ runtime library used to build the tool and … Read more

Class based component constructor and supper()

Summary A common React error occurs when developers omit super() in class component constructors or misunderstand its purpose. The super() call is mandatory in JavaScript class constructors that define their own constructor and intend to use this. It initializes the parent class instance, making this available in the derived class. React enforces this rule because … Read more