I O exception while trying to read – How to solve this Elasticsearch error

Opster Team

Aug-23, Version: 6.8-8.2

Briefly, this error occurs when Elasticsearch encounters an issue while trying to read data, possibly due to a network problem, disk I/O issue, or corrupted data. To resolve this, you can try the following: 1) Check the health of your network connection. 2) Inspect your disk for any I/O issues. 3) Validate your data to ensure it’s not corrupted. 4) If the error persists, consider restarting your Elasticsearch node or cluster. Always ensure you have a backup of your data to prevent loss.

We recommend you run Elasticsearch Error Check-Up which can resolve issues that cause many errors.

Advanced users might want to skip right to the common problems section in each concept or try running the Check-Up which analyses ES to pinpoint the cause of many errors and provides suitable actionable recommendations how to resolve them (free tool that requires no installation).

Quick Overview

Elasticsearch reads the value of vm.max_map_count from the file /proc/sys/vm/max_map_count in case of a Linux based operating system. and in rare cases, when this file isn’t present or Elasticsearch isn’t able to read the file, it throws the I/O exception. Fix:  This warning appears in specific and uncommon circumstances, such as when the Elasticsearch process isn’t able to read the file or the file itself isn’t present or has been deleted. In order to fix the issue, ensure the file is present and that the Elasticsearch process has read access. You could also try changing the values slightly using the root use to make sure the file is not corrupt. Please see Elasticsearch source code useful for this.

Log Context

Log “I/O exception while trying to read [{}]” classname is BootstrapChecks.java.
We extracted the following from Elasticsearch source code for those seeking an in-depth context :

                    } catch (final NumberFormatException e) {
                        logger.warn(() -> new ParameterizedMessage("unable to parse vm.max_map_count [{}]"; rawProcSysVmMaxMapCount); e);
            } catch (final IOException e) {
                logger.warn(() -> new ParameterizedMessage("I/O exception while trying to read [{}]"; path); e);
            return -1;

        @SuppressForbidden(reason = "access /proc/sys/vm/max_map_count")


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