You know you shouldn’t use showModalDialog to open modal windows – it’s bad taste and prone to cause issues. Unfortunately many applications (especially Enterprise ones) rely on the method ability to halt code execution until the window closed (e.g. user answers a YES/NO question).

Tough luck, starting version 37 Google Chrome removed support for showModalDialog . Your code suddenly began to act in weird and unpredictable way. You definitely should rework it to use a different approach to dialogs. Fortunately Google gives you a bit more time. You can re-enable showModalDialog support, but only temporarily – until May of 2015.

Here’s how to do it in Chrome for Windows. Open Registry Editor (regedit) and create following keys:

HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Google\Chrome\EnableDeprecatedWebPlatformFeatures

Under the EnableDeprecatedWebPlatformFeatures key create a string value with name 1 and value of ShowModalDialog_EffectiveUntil20150430. To verify that the policy is enabled, visit chrome://policy URL.

UPDATE If the above didn’t work for you here’s another method to try (Thank you, Yuhong Bao).