What is the PLG file format?
A .plg file is a Microsoft Developer Studio build log, automatically generated by the Visual C++ 5.0 and 6.0 IDEs (1997-1998) each time a project is compiled. The file records the complete compiler output for a build: each source file processed, any warnings or errors issued, and a final summary of error and warning counts.
Despite its .plg extension, the file is formatted as HTML. It begins with standard <html> and <body> tags, uses an <h1> heading for the project configuration name, and wraps compiler output in <pre> blocks - meaning it opens correctly in any web browser. The content is plain text encoded in Windows-1252 (ANSI).
.plg files are found in Visual C++ project directories alongside .dsp (project) and .dsw (workspace) files. They are purely informational: deleting a .plg file has no effect on the project, its source code, or subsequent builds. Developer Studio regenerates the file automatically on the next build.
The format is specific to the pre-2002 Developer Studio IDE. Visual Studio .NET (2002) and all subsequent versions switched to plain .log files, and Visual Studio 2017 introduced MSBuild's .binlog binary log format. Users encounter .plg files today only when working with legacy VC++ 5.0 or 6.0 projects from the late 1990s.
Security & safety
RISK: LOWPLG files are plain HTML text containing only build log output - they contain no executable code and no scripts. Standard caution for HTML files applies: in the unlikely event the project name or path contains HTML entities, a browser rendering the file is still safe (no JavaScript in typical PLG files).
Format details
in a nutshellPrograms that open PLG files
Windows5 apps
Microsoft Visual Studio
Paid Can open .plg as a text file; historical context only - modern Visual Studio does not generate .plg files. 
Notepad
Open-source File → Open the .plg file; Notepad++ auto-detects HTML syntax and highlights it. 
Any web browser (Chrome, Firefox, Edge)
Free Double-click the .plg file - Windows may not recognise the extension. Right-click → Open with → Browser of choice. HTML renders with light formatting.
Notepad (built-in)
Built-in Right-click the .plg → Open with → Notepad to read the raw HTML as text. Technical details
deep spec| File format | HTML text (despite the non-HTML extension); opens correctly in any web browser |
| Text encoding | Windows-1252 (ANSI); occasionally plain ASCII for all-ASCII project paths and output |
| HTML structure | <html><body> wrapper; <h1> heading with project and configuration name; compiler output in <pre> blocks; final build result line |
| Generation | Automatically created or overwritten by Microsoft Developer Studio on each build; no user action required |
| Content scope | Full compiler output per .c / .cpp source file (warnings, errors), linker output, and aggregate error/warning counts |
| Effect of deleting | None - Developer Studio recreates the file automatically on the next build |
| Associated project files | Found alongside .dsp (project definition) and .dsw (workspace) files in the VC++ project directory |
| IDE compatibility | Microsoft Developer Studio (Visual C++ 4.x-6.0, 1995-1998); not generated by Visual Studio 2002 or later |
| Typical file size | 1 KB - 500 KB for typical builds; large projects with many compiler errors may reach several MB |
| Successor format | Visual Studio 2002+ uses .log (plain text); Visual Studio 2017+ supports .binlog (MSBuild binary log) |
| Operating system | Windows only (Microsoft Developer Studio ran exclusively on Windows) |
| Released | ~1993-1994 (Microsoft Developer Studio, Visual C++ 2.x era) |
PLG conversions
Community Q&A
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