Error "Request header is too large" after using the Update All action on a List. Or, using Update All results in a transaction timeout.SummaryLists on ServiceNow provide an action titled "Update All" which can be used to update a batch of records with identical data. For example, if you need to modify 2 or more record's "Description" field to the same text you can use the Update All action. ServiceNow documentation for this feature can be found here: https://docs.servicenow.com/bundle/sandiego-platform-user-interface/page/use/using-lists/task/t_EditMultiRecUsingEditingForm.html A common error that can arise when using this action is "HTTP 400 Request header is too large". Typically you'll receive this error within a few moments of submitting your update. However, due to the error, the action is not taken and the selected records will still be as they were. Another issue that may come up is that your transaction times out and does fully complete - a number of records that were part of your update will be untouched while others may have actually updated. The Update All action has some technical limitations that unfortunately ServiceNow is unable to improve upon. If you happen to come across either of these, here are a few steps you can take to work around them: 1. Limit the amount of records you're updating. if you notice your update is taking too long to complete - or if the update times out after 3 minutes - this may be due to a large record set that needs more time to process. As mentioned, the default time limit for most basic transactions in ServiceNow is 3 minutes. Anything that runs past this limit is automatically terminated by the platform in order to save time and server resources for other users. The easiest way to get around this is to do small batch updates with less records. For example, if updating 5000 records at once takes longer than 3 minutes, you'll want to lower the amount of records updated on a single transaction. Try submitting 100 or 500 at a time instead. 2. Limit any query conditions on the List before selecting "Update All". This can be an effective workaround to both issues described above due to their underlying causes. If the HTTP 400 error is seen, this is usually due to an excessively long query and can only be mitigated by shortening it. If the transaction times out and you've already attempted to cut-back on the amount of records, shortening the query conditions can help the platform search for the selected records faster and in turn speed up the entire process. 3. Ask your system administrator to submit the update on your behalf. Admins have the ability to submit updates via "script" on the platform. These types of transactions have a default limit of 4 hours (much more than the basic 3 minutes) which should allow enough time for almost any basic update. Anything that requires more time than this should require a consultation with your administrator regardless.