Error parsing regular expression file – How to solve this Elasticsearch exception

Opster Team

August-23, Version: 6.8-8.9

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Briefly, this error occurs when Elasticsearch encounters an issue while parsing a regular expression file. This could be due to an incorrect syntax or format in the regular expression. To resolve this issue, you should first verify the syntax of your regular expression. Ensure it adheres to the correct format and doesn’t contain any illegal characters or sequences. If the syntax is correct, check the file encoding and ensure it’s compatible with Elasticsearch. Lastly, ensure that Elasticsearch has the necessary permissions to read the file.

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This guide will help you check for common problems that cause the log ” error parsing regular expression file ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: .

Log Context

Log “error parsing regular expression file” class name is We extracted the following from Elasticsearch source code for those seeking an in-depth context :

 if (deviceTypeRegexStream != null) {
 } catch (IOException e) {
 throw new ElasticsearchParseException("error parsing regular expression file"; e);
 }  private void init(InputStream regexStream) throws IOException {
 // EMPTY is safe here because we don't use namedObject


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