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Burp Scanner error reference

  • Last updated: November 24, 2021

  • Read time: 17 Minutes

This is a quick reference guide to troubleshooting the most common Burp Scanner error messages. You can use Ctrl/Cmd + F to search for the error you've encountered to see more detailed information about the potential cause of the problem and some remediation advice. If you cannot find your error message listed, please contact our support team for more assistance.

Can't find existing log file!

Cause

Our technical support team may have asked you to enable debug logging for a scan in order to help diagnose a problem you reported. This creates a log file called something like crawlDebug-1-1234567890123.log when the scan runs. Burp Suite tried to load a scan at startup, but could not find the associated log file. This could be because it has been moved or deleted.

Remedy

If you moved this file from its original location, put it back and try again. To find the expected location:

  1. From the Burp's Dashboard tab, click the settings icon for the related scan.
  2. Go to the Scan Configuration settings, select the relevant crawl configuration, then click Edit.
  3. Under Crawl Optimization, click the settings icon next to the Crawl strategy menu.
  4. Check the Directory field.
Note

The logging option is not recommended for normal operation. Generally speaking, you should only enable it when asked to do so by our support team.

Can't write to log file:

Cause

Our technical support team may have told you to enable debug logging for a scan in order to help diagnose a problem you reported. This creates a log file called something like crawlDebug-1-1234567890123.log when the scan runs. Burp Scanner encountered errors while trying to write to this file. This could be caused by permissions or other file system problems with the location you have selected for the log file.

Remedy

Make sure that the burpsuite user has permission to write to the specified directory, or select a different directory to save the log file in.

Note

The logging option is not recommended for normal operation. Generally speaking, you should only enable it when asked to do so by our support team.

Failed to replay sequence

Cause

Burp Scanner was unable to successfully replay one or more steps of a recorded login sequence during the scan.

Remedy

Contact our Support team with the following:

  1. An HTML snippet of the login form.
  2. The login script (JSON) exactly as it is pasted into Burp.
  3. A screen recording of the login sequence being performed by Burp Scanner. To do this, under Application Login, select your recorded login sequence and click Replay.
  4. A screenshot of the event log (if any errors are visible) and the diagnostics from Help > Diagnostics.

Cannot replay sequence, failed to create a browser

Cause

Burp Scanner was unable to start the embedded browser that it uses to replay recorded login sequences.

Remedy

Run the Embedded browser health check from the Help menu in Burp Suite. This will diagnose problems with the embedded browser.

Skipping API definition. The data in the definition file is malformed and cannot be read by Burp Scanner

Cause

Burp Scanner needs to be able to parse an API definition in order to scan it. Currently, this is only possible for definitions that:

  • Meet the OpenAPI version 3.x.x specification.
  • Do not contain any external references.

Any definitions that do not meet these requirements will be skipped during the scan.

Remedy

Make sure that the API definition you're trying to scan meets the prerequisites outlined above. For more details, please refer to the documentation for API scanning.

Environment not supported by browser. (Use 'Embedded Browser Health Check' for more details.)

Cause

Burp Scanner could not start the embedded browser as it is not supported by the current operating system environment.

Remedy

Run the Embedded browser health check from the Help menu in Burp Suite. This will diagnose problems with the embedded browser.

Could not start browser. (Use 'Embedded Browser Health Check' for more details.)

Cause

Burp Scanner could not start the embedded browser due to an unexpected error.

Remedy

Run the Embedded browser health check from the Help menu in Burp Suite. This will diagnose problems with the embedded browser.

Could not start embedded browser sandbox because you are running as root. Either switch to running as an unprivileged user or allow running without sandbox

Cause

For security reasons, on Linux, the embedded browser runs in sandbox mode by default. When logged in as root, this may prevent the browser from launching properly.

Remedy

You have the following options:

  1. Switch to a different user. We recommend this option wherever possible.
  2. Allow the embedded browser to run without a sandbox under Project options > Misc > Embedded browser.
Warning

Scanning hostile websites without a sandbox can increase the risk of your local machine being compromised. Before enabling this option, make sure that you understand the security implications.

Can not start embedded browser sandbox because your kernel does not support user namespaces. Please either upgrade your kernel or allow running without sandbox

Cause

Running the embedded browser in sandbox mode on Linux requires a Kernel that supports User namespaces.

Remedy

You can either upgrade to a Kernel that supports namespaces or allow Burp Scanner's embedded browser to run without the sandbox under Project options > Misc > Embedded browser.

Warning

Scanning hostile websites without a sandbox can increase the risk of your local machine being compromised. Before enabling this option, make sure that you understand the security implications.

Can not start embedded browser sandbox because the chrome-sandbox binary is not configured correctly and your kernel has user namespace cloning disabled. To enable, run the following command as root: "echo 1 > /proc/sys/kernel/unprivileged_userns_clone"

Cause

Burp Scanner will by default run the embedded browser in sandbox mode. This requires an operating system environment that supports namespace cloning. Sandbox mode is a security feature of Chromium that makes browsing more secure.

Remedy

If you enable namespace cloning the embedded browser can run in sandbox mode. Running the command in the error message will enable namespace cloning until you reboot. You can save this setting in your sysctl.conf file to enable this setting permanently. Please refer to the documentation for your operating system for more details.

Can not start embedded browser sandbox because the chrome-sandbox binary is not configured correctly and your kernel has user namespace cloning disabled. To enable, run the following command as root: "echo 0 > /proc/sys/kernel/userns_restrict"

Cause

Burp Scanner will by default run the embedded browser in sandbox mode. This requires an operating system environment that supports namespace cloning. Sandbox mode is a security feature of Chromium that makes browsing more secure.

Remedy

If you enable namespace cloning the embedded browser can run in sandbox mode. Running the command in the error message will enable namespace cloning until you reboot. You can save this setting in your sysctl.conf file to enable this setting permanently. Please refer to the documentation for your operating system for more details.

Cannot handle streaming response:

Cause

Burp Scanner does not support streaming responses. It will skip pages that provide a streaming response.

Remedy

You can test streaming responses using Burp Suite's manual tool. For more information, please refer to the documentation on streaming responses.

Error generating report:

Cause

Burp Scanner encountered a file system error when trying to open or write to the scan report file. This can be caused by permissions or other file system errors.

Remedy

Check that the burpsuite user has permission to write to the folder you are trying to save the report to or try saving the report to a different folder.

The Burp Collaborator server used by the Burp Collaborator client is not reachable, change the settings to use this feature.

Cause

The Burp Collaborator client was unable to connect to the Burp Collaborator server that it uses to perform OAST checks. As a result, these checks were skipped for this scan.

Remedy

Run the Collaborator Server health check and double-check the Collaborator server settings for the server in the Project options > Misc tab.

Failed to connect to the configured Collaborator server.

Cause

Burp Scanner was unable to connect to the selected Burp Collaborator server. As a result, OAST checks were skipped for this scan.

Remedy

Run the Collaborator Server health check and double-check the Collaborator server settings for the server in the Project options > Misc tab.

Skipping current scanner check for too many consecutive unknown host errors have occurred

Cause

Burp Scanner could not resolve a hostname when making a request during the audit phase. This can be caused by a number of issues, including intermittent network problems, server load, or security measures like Web Application Firewalls.

Remedy

Experiencing intermittent problems accessing a site is normal and does not necessarily indicate a problem. Scans may overload servers and the unusual activity may cause Web Application Firewalls to start blocking requests, for example. To help avoid these issues, you can configure resource pools to control the number of requests you're sending and how frequently. By default, Burp Scanner will mark any failed requests for a follow-up pass, but you can also configure it to make more passes.

Skipping current insertion point for too many consecutive unknown host errors have occurred

Cause

Burp Scanner could not resolve a hostname when making a request during the audit phase. This can be caused by a number of issues, including intermittent network problems, server load, or security measures like Web Application Firewalls.

Remedy

Experiencing intermittent problems accessing a site is normal and does not necessarily indicate a problem. Scans may overload servers and the unusual activity may cause Web Application Firewalls to start blocking requests, for example. To help avoid these issues, you can configure resource pools to control the number of requests you're sending and how frequently. By default, Burp Scanner will mark any failed requests for a follow-up pass, but you can also configure it to make more passes.

Skipping phase X for too many consecutive unknown host errors have occurred

Cause

Burp Scanner could not resolve a hostname when making a request during the audit phase. This can be caused by a number of issues, including intermittent network problems, server load, or security measures like Web Application Firewalls.

Note

The error message will show an alphanumeric reference like A1.

Remedy

Experiencing intermittent problems accessing a site is normal and does not necessarily indicate a problem. Scans may overload servers and the unusual activity may cause Web Application Firewalls to start blocking requests, for example. To help avoid these issues, you can configure resource pools to control the number of requests you're sending and how frequently. By default, Burp Scanner will mark any failed requests for a follow-up pass, but you can also configure it to make more passes.

Skipping current scanner check for too many consecutive request timeout errors have occurred

Cause

Burp Scanner identifies insertion points where it can try injecting different payloads. Repeated attempts to insert a payload into the current insertion point or the current page have failed.

Remedy

Experiencing intermittent problems accessing a site is normal and does not necessarily indicate a problem. Scans may overload servers and the unusual activity may cause Web Application Firewalls to start blocking requests, for example. To help avoid these issues, you can configure resource pools to control the number of requests you're sending and how frequently. By default, Burp Scanner will mark any failed requests for a follow-up pass, but you can also configure it to make more passes.

Skipping current insertion point for too many consecutive request timeout errors have occurred

Cause

Burp Scanner identifies insertion points where it can try injecting different payloads. Repeated attempts to insert a payload into the current insertion point or the current page have failed.

Remedy

Experiencing intermittent problems accessing a site is normal and does not necessarily indicate a problem. Scans may overload servers and the unusual activity may cause Web Application Firewalls to start blocking requests, for example. To help avoid these issues, you can configure resource pools to control the number of requests you're sending and how frequently. By default, Burp Scanner will mark any failed requests for a follow-up pass, but you can also configure it to make more passes.

Skipping phase X for too many consecutive request timeout errors have occurred

Cause

Burp Scanner identifies insertion points where it can try injecting different payloads. Repeated attempts to insert a payload into the current insertion point or the current page have failed.

Note

The error message will show an alphanumeric reference like A1.

Remedy

Experiencing intermittent problems accessing a site is normal and does not necessarily indicate a problem. Scans may overload servers and the unusual activity may cause Web Application Firewalls to start blocking requests, for example. To help avoid these issues, you can configure resource pools to control the number of requests you're sending and how frequently. By default, Burp Scanner will mark any failed requests for a follow-up pass, but you can also configure it to make more passes.

Skipping current scanner check for too many consecutive crawled location no longer reachable errors have occurred

Cause

Burp Scanner's crawl engine accesses URLs in the same way as a human accessing a website would. It starts at the specified URLs and follows links through a website. A page discovered during the crawl could no longer be found by following links from the specified starting URL, although it might still exist on the site.

Remedy

Experiencing intermittent problems accessing a site is normal and does not necessarily indicate a problem. Scans may overload servers and the unusual activity may cause Web Application Firewalls to start blocking requests, for example. To help avoid these issues, you can configure resource pools to control the number of requests you're sending and how frequently. By default, Burp Scanner will mark any failed requests for a follow-up pass, but you can also configure it to make more passes.

Skipping current insertion point for too many consecutive crawled location no longer reachable errors have occurred

Cause

Burp Scanner's crawl engine accesses URLs in the same way as a human accessing a website would. It starts at the specified URLs and follows links through a website. A page discovered during the crawl could no longer be found by following links from the specified starting URL, although it might still exist on the site.

Remedy

Experiencing intermittent problems accessing a site is normal and does not necessarily indicate a problem. Scans may overload servers and the unusual activity may cause Web Application Firewalls to start blocking requests, for example. To help avoid these issues, you can configure resource pools to control the number of requests you're sending and how frequently. By default, Burp Scanner will mark any failed requests for a follow-up pass, but you can also configure it to make more passes.

Skipping phase X for too many consecutive crawled location no longer reachable errors have occurred

Cause

Burp Scanner's crawl engine accesses URLs in the same way as a human accessing a website would. It starts at the specified URLs and follows links through a website. A page discovered during the crawl could no longer be found by following links from the specified starting URL, although it might still exist on the site.

Note

The error message will show an alphanumeric reference like A1.

Remedy

Experiencing intermittent problems accessing a site is normal and does not necessarily indicate a problem. Scans may overload servers and the unusual activity may cause Web Application Firewalls to start blocking requests, for example. To help avoid these issues, you can configure resource pools to control the number of requests you're sending and how frequently. By default, Burp Scanner will mark any failed requests for a follow-up pass, but you can also configure it to make more passes.

Skipping current scanner check for too many consecutive insertion point no longer present errors have occurred

Cause

Burp Scanner's audit phase cannot find an insertion point identified during the crawl phase. This can happen for a number of reasons and may not represent a problem. Intermittent connection issues can prevent pages from loading properly. Testing a Web Application can put a server under unusual load, leading to pages not loading properly. A Web Application Firewall can detect unusual activity and start blocking requests.

Remedy

Experiencing intermittent problems accessing a site is normal and does not necessarily indicate a problem. Scans may overload servers and the unusual activity may cause Web Application Firewalls to start blocking requests, for example. To help avoid these issues, you can configure resource pools to control the number of requests you're sending and how frequently. By default, Burp Scanner will mark any failed requests for a follow-up pass, but you can also configure it to make more passes.

Skipping current insertion point for too many consecutive insertion point no longer present errors have occurred

Cause

Burp Scanner's audit phase cannot find an insertion point identified during the crawl phase. This can happen for a number of reasons and may not represent a problem. Intermittent connection issues can prevent pages from loading properly. Testing a Web Application can put a server under unusual load, leading to pages not loading properly. A Web Application Firewall can detect unusual activity and start blocking requests.

Remedy

Experiencing intermittent problems accessing a site is normal and does not necessarily indicate a problem. Scans may overload servers and the unusual activity may cause Web Application Firewalls to start blocking requests, for example. To help avoid these issues, you can configure resource pools to control the number of requests you're sending and how frequently. By default, Burp Scanner will mark any failed requests for a follow-up pass, but you can also configure it to make more passes.

Skipping phase X for too many consecutive insertion point no longer present errors have occurred

Cause

Burp Scanner's audit phase cannot find an insertion point identified during the crawl phase. This can happen for a number of reasons and may not represent a problem. Intermittent connection issues can prevent pages from loading properly. Testing a Web Application can put a server under unusual load, leading to pages not loading properly. A Web Application Firewall can detect unusual activity and start blocking requests.

Note

The error message will show an alphanumeric reference like A1.

Remedy

Experiencing intermittent problems accessing a site is normal and does not necessarily indicate a problem. Scans may overload servers and the unusual activity may cause Web Application Firewalls to start blocking requests, for example. To help avoid these issues, you can configure resource pools to control the number of requests you're sending and how frequently. By default, Burp Scanner will mark any failed requests for a follow-up pass, but you can also configure it to make more passes.

Skipping current scanner check for too many consecutive streaming response errors have occurred

Cause

Burp Scanner does not support streaming responses. It will skip URLs that provide streaming responses.

Remedy

You can test streaming responses using Burp Suite's manual tool. For more information, please refer to the documentation on streaming responses.

Skipping current insertion point for too many consecutive streaming response errors have occurred

Cause

Burp Scanner does not support streaming responses. It will skip URLs that provide streaming responses.

Remedy

You can test streaming responses using Burp Suite's manual tool. For more information, please refer to the documentation on streaming responses.

Skipping phase X for too many consecutive streaming response errors have occurred

Cause

Burp Scanner does not support streaming responses. It will skip URLs that provide streaming responses.

Note

The error message will show an alphanumeric reference like A1.

Remedy

You can test streaming responses using Burp Suite's manual tool. For more information, please refer to the documentation on streaming responses.

Skipping current scanner check for too many consecutive embedded browser crash errors have occurred

Cause

Burp Scanner's embedded browser crashed while requesting a URL.

Remedy
  • By default, Burp Scanner will mark any failed requests for a follow-up pass, but you can also configure it to make more passes.
  • If this occurs repeatedly on a single site, try manually navigating to the page and see if it crashes the browser while browsing manually.
  • If this occurs on multiple sites, try running the embedded browser health check.

Skipping current insertion point for too many consecutive embedded browser crash errors have occurred

Cause

Burp Scanner's embedded browser crashed while requesting a URL.

Remedy
  • By default, Burp Scanner will mark any failed requests for a follow-up pass, but you can also configure it to make more passes.
  • If this occurs repeatedly on a single site, try manually navigating to the page and see if it crashes the browser while browsing manually.
  • If this occurs on multiple sites, try running the embedded browser health check.

Skipping phase X for too many consecutive embedded browser crash errors have occurred

Cause

Burp Scanner's embedded browser crashed while requesting a URL.

Note

The error message will show an alphanumeric reference like A1.

Remedy
  • By default, Burp Scanner will mark any failed requests for a follow-up pass, but you can also configure it to make more passes.
  • If this occurs repeatedly on a single site, try manually navigating to the page and see if it crashes the browser while browsing manually.
  • If this occurs on multiple sites, try running the embedded browser health check.

Found 0 new locations after logging in

Cause

Burp Scanner keeps track of whether or not the page shown after logging in is different from the page shown before logging in. In this case, after logging in, the pages available were not significantly different. This does not necessarily mean the login failed, but this is one possible cause.

Remedy
  • Double-check your application login settings to make sure the provided credentials are correct.
  • Run Burp Scanner in headed mode and watch it attempt to log in to see if you can spot any issues.
  • Try using a recorded login sequence if you aren't already. This allows Burp Scanner to handle much more complex login forms, like those featuring iFrames and SSO.

Maximum time exceeded in dynamic code analysis of:

Cause

Burp Scanner will execute and analyze JavaScript as it scans a site. To avoid it becoming bogged down, it can be configured with a time limit for how long it tries to do this for a single request. This error means that a page has exceeded this time limit set in Burp Suite. By default, this is set to 30 seconds, but you can adjust this in the audit options under JavaScript Analysis.

Remedy

You can change the timeout setting in the settings for the audit under JavaScript analysis.

Note

The default setting is 30 seconds.

Failed to lookup host X while crawling.

Cause

Burp Scanner was unable to crawl a location because it could not resolve the hostname. This can be caused by either an incorrect hostname in the URLs provided.

Remedy

Check for typos or other errors in the URLs to Scan.

X consecutive requests have failed.

Cause

During the crawl phase, the scan will automatically be paused if more than 10 consecutive requests fail. This prevents the scan from needlessly crawling a site that is currently down, for example.

Remedy

Check that the web application being scanned is still running and accessible.

You can also adjust the number of consecutive failed requests that cause Burp Scanner to pause the crawl in the crawl options under Handling Application Errors During Crawl.

More than X percent of requests have failed.

Cause

During the crawl phase, the scan can automatically be paused if more than a certain percentage of requests fail. This prevents the scan from needlessly crawling a site that is currently down, for example.

Remedy

Check that the web application being scanned is still running and accessible.

You can also adjust the number of consecutive failed requests that cause Burp Scanner to pause the crawl in the crawl options under Handling Application Errors During Crawl.

Could not connect to any seed URLs.

Cause

Burp Scanner was unable to send requests to any of the specified URLs to scan. This error can be caused by anything that prevents Burp Scanner from connecting to the URL. This can include timeouts, connection failed errors, and problems resolving hostnames.

Remedy
  • Check for typos and other errors in the URLs to Scan.
  • Check that you are able to connect to the target application from the machine running the scan.
  • If you have any trouble doing this, troubleshoot your connection to the hostname that is failing.
  • Check the firewall, proxy, and DNS server settings for the machine running the scan.

Crawl was configured to use embedded browser, but a browser could not be started

Cause

Burp Scanner was unable to start the embedded browser. This can be caused by various issues with the embedded browser.

Remedy

Run the Embedded browser health check from the Help menu in Burp Suite. This will diagnose problems with the embedded browser.

Cannot continue crawl started before version

Cause

Burp Scanner's crawl engine sometimes gets updated in such a way that it cannot open files created in previous versions. While this happens relatively infrequently, it can happen when adding new features or significantly changing how it operates.

Remedy

Recreate your scan in the new version.