FixerCode — Error Code Reference Updates https://fixercode.com Independent reference for web, software, and OS errors with clear explanations and context. en-us Sat, 29 Aug 2026 00:00:00 GMT Linux 129 — Connection Hangup — the controlling terminal closed; daemons repurpose it as a config-reload trigger https://fixercode.com/os/linux/system-errors/error-129 Exit code 129 is 128 + 1, the shell's report that the process died from SIGHUP. The signal was born for physical line dropouts, but modern daemons flipped its meaning: for many servers SIGHUP is the conventional reload signal, so the same delivery can mean routine maintenance or the death of a termi Sat, 29 Aug 2026 00:00:00 GMT https://fixercode.com/os/linux/system-errors/error-129 Linux 131 — Quit Signal — a Ctrl+\ interrupt that terminates the process and leaves a core dump https://fixercode.com/os/linux/system-errors/error-131 Exit code 131 encodes 128 + 3: the process died from SIGQUIT, the signal Ctrl+\ sends, and by default the death leaves a core dump for post-mortem reading. Sat, 29 Aug 2026 00:00:00 GMT https://fixercode.com/os/linux/system-errors/error-131 Linux 132 — Illegal Instruction — the CPU reached an opcode it cannot decode or execute https://fixercode.com/os/linux/system-errors/error-132 Exit code 132 maps to 128 + 4. The killer is SIGILL, raised when the processor meets an opcode outside the set it implements — the memory address itself may be perfectly valid. Sat, 29 Aug 2026 00:00:00 GMT https://fixercode.com/os/linux/system-errors/error-132 Linux 133 — Trace Trap — a breakpoint or trap instruction fired, normally under a debugger's control https://fixercode.com/os/linux/system-errors/error-133 Exit code 133 combines 128 with signal 5, SIGTRAP — the breakpoint signal debuggers live on, firing when a trap instruction executes with nobody positioned to absorb it. Sat, 29 Aug 2026 00:00:00 GMT https://fixercode.com/os/linux/system-errors/error-133 Linux 134 — Self-Abort — the process called abort() after detecting a state it cannot recover from https://fixercode.com/os/linux/system-errors/error-134 Exit code 134 is the arithmetic of 128 + 6, and the sender is the process itself: SIGABRT fires when abort() runs after an internal check declares the state unrecoverable. Sat, 29 Aug 2026 00:00:00 GMT https://fixercode.com/os/linux/system-errors/error-134 Linux 135 — Bus Error — a memory access rejected at the hardware level, often around mmap'd files https://fixercode.com/os/linux/system-errors/error-135 Exit code 135 = 128 + 7, SIGBUS. The memory access died on the hardware path — most often a mapped file whose bytes vanished underneath the mapping. Sat, 29 Aug 2026 00:00:00 GMT https://fixercode.com/os/linux/system-errors/error-135 Linux 136 — Arithmetic Fault — an integer division by zero or similar math trap, despite the name https://fixercode.com/os/linux/system-errors/error-136 Exit code 136 carries 128 + 8, SIGFPE. In practice the trigger is an integer division by zero; the floating-point name is a historical leftover. Sat, 29 Aug 2026 00:00:00 GMT https://fixercode.com/os/linux/system-errors/error-136 Linux 138 — User Signal 1 — an application-defined control channel rather than an error state https://fixercode.com/os/linux/system-errors/error-138 Exit code 138 decodes to 128 + 10, a USR1 delivery. What that delivery meant depends on the target program's handler table: a log reopen for one daemon, a state dump for another, and a plain kill for a process that never registered a handler. Sat, 29 Aug 2026 00:00:00 GMT https://fixercode.com/os/linux/system-errors/error-138 Linux 140 — User Signal 2 — the second application-defined channel, with a meaning set per program https://fixercode.com/os/linux/system-errors/error-140 Exit code 140 resolves to 128 + 12, the second user channel. USR2 has no built-in meaning; the target's handler — or lack of one — decides the outcome. Sat, 29 Aug 2026 00:00:00 GMT https://fixercode.com/os/linux/system-errors/error-140 Linux 141 — Broken Pipe — the process wrote into a pipe whose reader is already gone https://fixercode.com/os/linux/system-errors/error-141 Exit code 141 equals 128 + 13, SIGPIPE: a write landed on a pipe or socket whose reader had already left, and the kernel ended the writer. Sat, 29 Aug 2026 00:00:00 GMT https://fixercode.com/os/linux/system-errors/error-141 Linux 142 — Timer Expired — an alarm() deadline the process set for itself has run out https://fixercode.com/os/linux/system-errors/error-142 Exit code 142 stands for 128 + 14, SIGALRM — a deadline the process armed for itself through alarm() or an interval timer finally ran out, converting an internal watchdog or self-imposed timeout into an exit the shell reports like any other signal death. Sat, 29 Aug 2026 00:00:00 GMT https://fixercode.com/os/linux/system-errors/error-142 Linux 143 — Termination Request — a polite shutdown signal the process may handle before exiting https://fixercode.com/os/linux/system-errors/error-143 Exit code 143 is the arithmetic for 128 + 15, SIGTERM: the standard shutdown request arrived and the process ended — gracefully when a handler got its cleanup window, or on the spot when none existed. Sat, 29 Aug 2026 00:00:00 GMT https://fixercode.com/os/linux/system-errors/error-143 Linux 4 — Interrupted Call — a signal arrived mid-operation; the call stopped and can simply be retried https://fixercode.com/os/linux/system-errors/error-4 Exit code 4 corresponds to EINTR, 'Interrupted system call'. It occupies a special place among error codes: nothing actually failed. A signal arrived while the process waited in a slow syscall — a read, an accept, a sleep — and the kernel broke the wait so the signal could be handled. The operation Sat, 29 Aug 2026 00:00:00 GMT https://fixercode.com/os/linux/system-errors/error-4 Linux 9 — Bad File Descriptor — the descriptor number is not open in this process's table https://fixercode.com/os/linux/system-errors/error-9 Exit code 9 corresponds to EBADF, 'Bad file descriptor'. Every process keeps a small numbered table of open files, sockets, and pipes; EBADF is what the kernel answers when a syscall asks for a row that is not there. The number may never have been opened, or it was open once and something closed it Sat, 29 Aug 2026 00:00:00 GMT https://fixercode.com/os/linux/system-errors/error-9 Linux 14 — Bad Address — the kernel could not reach the user-space buffer a syscall pointed at https://fixercode.com/os/linux/system-errors/error-14 Exit code 14 corresponds to EFAULT, 'Bad address'. Despite the name, nothing is wrong with anyone's RAM. The setting is the boundary between kernel and user space: a syscall was handed a pointer to a user-space buffer, and when the kernel reached across to read or write it, the memory was not there. Sat, 29 Aug 2026 00:00:00 GMT https://fixercode.com/os/linux/system-errors/error-14 Linux 16 — Resource Busy — the target exists, but another holder refuses to release it right now https://fixercode.com/os/linux/system-errors/error-16 Exit code 16 corresponds to EBUSY, 'Device or resource busy'. The defining fact is contention: the resource exists, is healthy, and simply has another owner. Unlike missing files or bad arguments, nothing is broken — the operation arrived at a busy moment, and the kernel declined to yank the resourc Sat, 29 Aug 2026 00:00:00 GMT https://fixercode.com/os/linux/system-errors/error-16 Linux 17 — File Exists — a create-with-exclusivity request collided with a name that is already there https://fixercode.com/os/linux/system-errors/error-17 Exit code 17 corresponds to EEXIST, 'File exists'. The errno only appears on demand: plain creation overwrites or merges happily, so EEXIST arises when the caller explicitly demanded exclusivity — create this only if it does not exist. The kernel found the name occupied and reported the collision in Sat, 29 Aug 2026 00:00:00 GMT https://fixercode.com/os/linux/system-errors/error-17 Linux 19 — No Such Device — the operation targets hardware or a driver that is not present https://fixercode.com/os/linux/system-errors/error-19 Exit code 19 corresponds to ENODEV, 'No such device'. The distinction from a missing file matters: the path may well exist — a device node sitting in /dev — but the hardware or driver that should answer behind it is gone. The kernel accepted the lookup and found nobody home. Sat, 29 Aug 2026 00:00:00 GMT https://fixercode.com/os/linux/system-errors/error-19 Linux 20 — Not a Directory — a path walks through a component that is an ordinary file https://fixercode.com/os/linux/system-errors/error-20 Exit code 20 corresponds to ENOTDIR, 'Not a directory'. Path resolution walks a path one component at a time, and every component except the last must be a directory to descend through. When the walk reaches an ordinary file standing where a directory should be, the kernel stops and reports errno 20 Sat, 29 Aug 2026 00:00:00 GMT https://fixercode.com/os/linux/system-errors/error-20 Linux 21 — Is a Directory — a file-level write or open was aimed at a directory https://fixercode.com/os/linux/system-errors/error-21 Exit code 21 corresponds to EISDIR, 'Is a directory'. POSIX draws a hard line: directories are namespace structures, not writable byte streams. Any operation that treats one as a file — opening it for writing, redirecting output into it, reading it as data through file interfaces — fails with errno Sat, 29 Aug 2026 00:00:00 GMT https://fixercode.com/os/linux/system-errors/error-21 Linux 22 — Invalid Argument — a syscall received a malformed or self-contradictory parameter https://fixercode.com/os/linux/system-errors/error-22 Exit code 22 corresponds to EINVAL, 'Invalid argument'. It is the syscall layer's generic rejection: the request itself is malformed, independent of system state. The file may exist, the device may be idle, the network may be perfect — none of it matters, because the arguments as given cannot be hon Sat, 29 Aug 2026 00:00:00 GMT https://fixercode.com/os/linux/system-errors/error-22 Linux 24 — Too Many Open Files — the process hit its per-process descriptor ceiling https://fixercode.com/os/linux/system-errors/error-24 Exit code 24 corresponds to EMFILE, 'Too many open files'. Every process owns a fixed-size table of descriptors, and EMFILE is the ceiling reached: open() and socket() fail not because resources are missing on disk or network, but because the process's own table has no free row left to record the ne Sat, 29 Aug 2026 00:00:00 GMT https://fixercode.com/os/linux/system-errors/error-24 Linux 28 — No Space Left — the filesystem ran out of data blocks or of inodes https://fixercode.com/os/linux/system-errors/error-28 Exit code 28 corresponds to ENOSPC, 'No space left on device'. The storage refused a write, and the interesting question is which table ran dry: the data blocks everyone checks first, or the inode table that allocates one entry per file regardless of size. A filesystem can be 90% empty by bytes and Sat, 29 Aug 2026 00:00:00 GMT https://fixercode.com/os/linux/system-errors/error-28 Linux 30 — Read-Only Filesystem — the mount itself refuses writes, so permission changes cannot help https://fixercode.com/os/linux/system-errors/error-30 Exit code 30 corresponds to EROFS, 'Read-only file system'. The refusal sits at the mount level, above any per-file permission: the whole filesystem was mounted without write access, so no ownership change, no chmod, and no correct user can write through it. The question is never 'who is allowed' bu Sat, 29 Aug 2026 00:00:00 GMT https://fixercode.com/os/linux/system-errors/error-30 Linux 32 — Broken Pipe — a write failed because the pipe's read end had already closed https://fixercode.com/os/linux/system-errors/error-32 Exit code 32 corresponds to EPIPE, 'Broken pipe'. A write into a pipe or socket requires a live reader on the other end; when the reader is gone, the kernel rejects the write with errno 32. The same event also raises SIGPIPE — exit code 141 is the shell's view of that signal, and EPIPE is the errno Sat, 29 Aug 2026 00:00:00 GMT https://fixercode.com/os/linux/system-errors/error-32 Chromium ERR_CONNECTION_REFUSED — Connection Refused — The target server actively rejected the connection attempt. https://fixercode.com/web/chromium/network-errors/err-connection-refused Chromium maps this to internal error code -102 (ERR_CONNECTION_REFUSED) and classifies it as a TCP connection-phase failure with NEL type "tcp.refused". The POSIX errno ECONNREFUSED is mapped to this code. The target server actively rejected the TCP SYN by returning a TCP RST packet, meaning no HTTP Tue, 11 Aug 2026 00:00:00 GMT https://fixercode.com/web/chromium/network-errors/err-connection-refused Chromium ERR_CONNECTION_TIMED_OUT — Connection Timed Out — The browser gave up waiting for a response from the server. https://fixercode.com/web/chromium/network-errors/err-connection-timed-out Chromium maps this to internal error code -118 (ERR_CONNECTION_TIMED_OUT) and classifies it as a TCP connection-phase failure with NEL type "tcp.timed_out". The browser sent a TCP SYN packet and received no response — neither SYN-ACK nor RST — so it waited for a hardcoded timeout before giving up. T Tue, 11 Aug 2026 00:00:00 GMT https://fixercode.com/web/chromium/network-errors/err-connection-timed-out Chromium ERR_SSL_PROTOCOL_ERROR — SSL Protocol Error — The secure connection failed during the TLS handshake. https://fixercode.com/web/chromium/network-errors/err-ssl-protocol-error Chromium maps this to internal error code -107 (ERR_SSL_PROTOCOL_ERROR) with NEL type "tls.protocol.error". This is a broad umbrella error covering any TLS handshake failure. Since Chrome 117, SHA-1 server signatures were deprecated (RFC 9155), breaking servers running old OpenSSL versions (1.0.1–1. Tue, 11 Aug 2026 00:00:00 GMT https://fixercode.com/web/chromium/network-errors/err-ssl-protocol-error CORS Missing Allow-Origin — No Access-Control-Allow-Origin Header — the response is missing the required CORS header. https://fixercode.com/web/cors/cross-origin/missing-allow-origin This is the most common CORS error. The browser successfully made the cross-origin HTTP request and received a full response, but the response lacked the Access-Control-Allow-Origin header. Chrome displays: "has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the r Tue, 11 Aug 2026 00:00:00 GMT https://fixercode.com/web/cors/cross-origin/missing-allow-origin CORS Preflight Failed — Preflight Request Rejected — the server OPTIONS response fails access control checks. https://fixercode.com/web/cors/cross-origin/preflight-failed When a frontend makes a complex cross-origin request (PUT, DELETE, custom headers, or JSON content type), the browser first sends an HTTP OPTIONS preflight. Chrome displays: "Response to preflight request doesn't pass access control check." The preflight must return a 200–299 status with the correct Tue, 11 Aug 2026 00:00:00 GMT https://fixercode.com/web/cors/cross-origin/preflight-failed CORS Header Not Allowed — Custom Header Blocked — the request header is not listed in Access-Control-Allow-Headers. https://fixercode.com/web/cors/cross-origin/header-not-allowed Even if the server allows the origin and HTTP method, it must also explicitly authorize every non-standard request header via Access-Control-Allow-Headers in the preflight response. Chrome displays: "Request header field X-Custom-Header is not allowed by Access-Control-Allow-Headers in preflight res Tue, 11 Aug 2026 00:00:00 GMT https://fixercode.com/web/cors/cross-origin/header-not-allowed CORS Credentials Not Supported — Wildcard with Credentials — the server used a wildcard origin while the request includes cookies. https://fixercode.com/web/cors/cross-origin/credentials-not-supported Browsers forbid sending cookies or HTTP auth to a server using a wildcard origin. Chrome displays: "The value of the 'Access-Control-Allow-Origin' header in the response must not be '*' when the request's credentials mode is 'include'." The server must echo the exact Origin instead of using * and al Tue, 11 Aug 2026 00:00:00 GMT https://fixercode.com/web/cors/cross-origin/credentials-not-supported CORS Multiple Allow-Origin — Duplicate Origin Headers — the response contains multiple Access-Control-Allow-Origin values. https://fixercode.com/web/cors/cross-origin/multiple-allow-origin The CORS spec allows exactly one Access-Control-Allow-Origin value: either a single origin or *. Chrome displays: "The 'Access-Control-Allow-Origin' header contains multiple values, but only one is allowed." This usually means CORS headers are added at multiple infrastructure layers — the applicatio Tue, 11 Aug 2026 00:00:00 GMT https://fixercode.com/web/cors/cross-origin/multiple-allow-origin Linux 1 — General Error — a non-specific failure in a command or script https://fixercode.com/os/linux/system-errors/error-1 Exit code 1 is a catch-all for many common Linux command failures. It indicates that the process finished with an error, but the specific reason was not mapped to a more descriptive exit code. Thu, 23 Jul 2026 00:00:00 GMT https://fixercode.com/os/linux/system-errors/error-1 Linux 2 — Shell Misuse — improper use of shell built-ins or syntax https://fixercode.com/os/linux/system-errors/error-2 Exit code 2 is reserved by the shell (like Bash) to indicate that a built-in command was used incorrectly or a syntax error was found in the script file itself. Thu, 23 Jul 2026 00:00:00 GMT https://fixercode.com/os/linux/system-errors/error-2 Linux 13 — Permission Denied — the process does not have permission to access the resource https://fixercode.com/os/linux/system-errors/error-13 Error 13 (EACCES) occurs when the kernel prevents a process from performing a file system operation due to existing permission bits (owner, group, others) or ACLs. Thu, 23 Jul 2026 00:00:00 GMT https://fixercode.com/os/linux/system-errors/error-13 Linux 126 — Command Not Executable — the file was found but is not executable https://fixercode.com/os/linux/system-errors/error-126 Exit code 126 occurs when the shell locates the file you specified, but the system refuses to run it as a process. This is distinct from error 127 where the file isn't found at all. Thu, 23 Jul 2026 00:00:00 GMT https://fixercode.com/os/linux/system-errors/error-126 Linux 127 — Exit Code 127 — shell command or executable binary not found https://fixercode.com/os/linux/system-errors/error-127 Exit code 127 is a standardized POSIX shell return status indicating that the shell or subshell attempted to execute a command, script, or binary that could not be located in the current environment's PATH search directories. Thu, 23 Jul 2026 00:00:00 GMT https://fixercode.com/os/linux/system-errors/error-127 Linux 130 — Terminated by User — the process was interrupted by a SIGINT signal https://fixercode.com/os/linux/system-errors/error-130 Exit code 130 is calculated as 128 + 2 (the signal number for SIGINT). it confirms that the process stopped because it received a manual interrupt signal. Thu, 23 Jul 2026 00:00:00 GMT https://fixercode.com/os/linux/system-errors/error-130 Linux 137 — Process Killed — the process was terminated by a SIGKILL signal https://fixercode.com/os/linux/system-errors/error-137 Exit code 137 is 128 + 9 (the signal number for SIGKILL). Unlike SIGTERM, SIGKILL cannot be caught or ignored by the process, resulting in an immediate exit. Thu, 23 Jul 2026 00:00:00 GMT https://fixercode.com/os/linux/system-errors/error-137 Linux 3 — Unspecified Error — a general-purpose failure code with no standardized meaning https://fixercode.com/os/linux/system-errors/error-3 Exit code 3 is not reserved by the POSIX standard or Bash. Individual programs assign their own meaning to it, making interpretation fully dependent on the specific application that generated the exit. Thu, 23 Jul 2026 00:00:00 GMT https://fixercode.com/os/linux/system-errors/error-3 Linux 11 — Signal 11 (SIGSEGV) — kernel signal for invalid memory reference segmentation fault https://fixercode.com/os/linux/system-errors/error-11 Signal 11, known as SIGSEGV (Segmentation Violation), is a standard POSIX signal sent by the Linux kernel when a process attempts to access a memory location that it does not have permission to access, or that does not exist in its address space. Uncaught, it terminates the process with exit code 13 Thu, 23 Jul 2026 00:00:00 GMT https://fixercode.com/os/linux/system-errors/error-11 Linux 139 — Exit Code 139 — process terminated by segmentation fault (Signal 11 / SIGSEGV) https://fixercode.com/os/linux/system-errors/error-139 Linux process exit code 139 indicates that an application was forcibly terminated by the operating system kernel due to a segmentation fault (Signal 11 / SIGSEGV). In Linux shell environments, fatal signal exit codes are calculated as 128 plus the signal number: 128 + 11 = 139. Thu, 23 Jul 2026 00:00:00 GMT https://fixercode.com/os/linux/system-errors/error-139 Linux 5 — Input/output error EIO — a read or write operation could not complete https://fixercode.com/os/linux/system-errors/error-5 Errno 5, commonly named EIO, means an input/output operation failed below the application layer. It can surface while reading, writing, opening, or executing through a path whose backing storage or filesystem layer could not complete the requested operation. Thu, 23 Jul 2026 00:00:00 GMT https://fixercode.com/os/linux/system-errors/error-5 Linux 12 — Out of Memory (ENOMEM) — the kernel cannot allocate the requested amount of memory https://fixercode.com/os/linux/system-errors/error-12 ENOMEM (errno 12) is returned by malloc, mmap, and other memory allocation calls when the kernel cannot satisfy the request. The Linux OOM Killer may terminate processes to recover memory before this error is returned. Thu, 23 Jul 2026 00:00:00 GMT https://fixercode.com/os/linux/system-errors/error-12 Linux 128 — Invalid Exit Argument — script exited with an out-of-range status or terminated by a signal https://fixercode.com/os/linux/system-errors/error-128 In Linux shell conventions, exit code 128 by itself means an invalid argument was passed to the exit built-in. More commonly, exit codes 128+N (e.g., 130 = 128+2 for SIGINT, 137 = 128+9 for SIGKILL) indicate the process was terminated by signal N. Thu, 23 Jul 2026 00:00:00 GMT https://fixercode.com/os/linux/system-errors/error-128 HTTP 206 — HTTP 206 Partial Content — the server is sending a requested range https://fixercode.com/web/http/status-codes/error-206 HTTP 206 Partial Content is a successful response for a range request. Instead of returning the entire resource like a normal 200 response, the server sends only the byte range or segment that the client requested. Sat, 27 Jun 2026 00:00:00 GMT https://fixercode.com/web/http/status-codes/error-206 HTTP 406 — Not Acceptable — the server cannot produce a response matching the request headers https://fixercode.com/web/http/status-codes/error-406 A 406 Not Acceptable response appears when the server understands the request but cannot generate a representation that satisfies the client's declared preferences. It is tied to content negotiation, where headers such as Accept or Accept-Language limit which response formats are considered valid. I Sat, 27 Jun 2026 00:00:00 GMT https://fixercode.com/web/http/status-codes/error-406 HTTP 501 — Not Implemented — the server does not support the HTTP method used in the request https://fixercode.com/web/http/status-codes/error-501 501 indicates a permanent limitation of the server — the feature or method requested is not supported. It differs from 405 which means the method is recognized but not permitted for that specific resource. Sat, 27 Jun 2026 00:00:00 GMT https://fixercode.com/web/http/status-codes/error-501 Nginx 499 — Client Closed Request — Nginx logged that the client closed the connection first https://fixercode.com/web/nginx/server-errors/error-499 Nginx 499 is a non-standard log status used when the client closes the connection before Nginx can finish sending the response. It usually appears in Nginx access logs rather than as a response a browser can display directly. The upstream application may still be processing when the disconnect happe Sat, 27 Jun 2026 00:00:00 GMT https://fixercode.com/web/nginx/server-errors/error-499