yiisoft/yii2 · error · yii\console\Exception

Unable to write output CSS file '{$outputFile}'.

Error message

Unable to write output CSS file '{$outputFile}'.

What it means

Error "Unable to write output CSS file '{$outputFile}'." thrown in yiisoft/yii2.

Source

Thrown at framework/console/controllers/AssetController.php:608

    }

    /**
     * Combines CSS files into a single one.
     * @param array $inputFiles source file names.
     * @param string $outputFile output file name.
     * @throws \yii\console\Exception on failure.
     */
    public function combineCssFiles($inputFiles, $outputFile)
    {
        $content = '';
        $outputFilePath = dirname($this->findRealPath($outputFile));
        foreach ($inputFiles as $file) {
            $content .= "/*** BEGIN FILE: $file ***/\n"
                . $this->adjustCssUrl(file_get_contents($file), dirname($this->findRealPath($file)), $outputFilePath)
                . "/*** END FILE: $file ***/\n";
        }
        if (!file_put_contents($outputFile, $content)) {
            throw new Exception("Unable to write output CSS file '{$outputFile}'.");
        }
    }

    /**
     * Adjusts CSS content allowing URL references pointing to the original resources.
     * @param string $cssContent source CSS content.
     * @param string $inputFilePath input CSS file name.
     * @param string $outputFilePath output CSS file name.
     * @return string adjusted CSS content.
     */
    protected function adjustCssUrl($cssContent, $inputFilePath, $outputFilePath)
    {
        $inputFilePath = str_replace('\\', '/', $inputFilePath);
        $outputFilePath = str_replace('\\', '/', $outputFilePath);

        $sharedPathParts = [];
        $inputFilePathParts = explode('/', $inputFilePath);
        $inputFilePathPartsCount = count($inputFilePathParts);

View on GitHub (pinned to 66f00d18a2)

When it happens

Trigger: Thrown at framework/console/controllers/AssetController.php:608 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of yiisoft/yii2@66f00d18a2 (2026-08-17). Data as JSON: /api/errors/21553e4c660d735b. Report an issue: GitHub.