Error code DLG_FLAGS_INVALID_CA is a common error that can occur in quite a few browsers.
There are some reasons that would trigger the error:
Then how to fix error code: DLG_FLAGS_INVALID_CA?
Try the methods mentioned below.

Here is how to do that:
Step 1: Typedatein theSearchbox and then clickDate & time tweaks.
Step 2: Turn onSet time automaticallyif it is disabled.
Step 3: Click theAdd clocks for different time zonesoption.

Step 4: Go to theInternet Timetab, click theChange parameters…button.
Step 6: give a shot to fire up the website to peek if error code DLG_FLAGS_INVALID_CA appears again.
Step 2: Go to theAdvancedtab and then setTime rangetoAll time.

Step 3: Check the box next toCached images and files, then clickClear data.
Step 4: Relaunch your web app to look to see if error code DLG_FLAGS_INVALID_CA is gone.
Here we take Chrome as an example:
Step 1: Open Chrome, click thethree-dotmenu to chooseSettings.

Step 2: Scroll down configs, click theAdvancedbutton.
Step 3: Then click theRestore parameters to their original defaultsoption, and then clickReset settingsto confirm the action.
Step 4: see if the error is fixed.

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Step 2: Go to theAdvancedtab, and then uncheck theWarn about certificate address mismatchbox.
Step 3: ClickApplyandOKto save the changes.
Step 4: reboot your system to test whether the error is fixed.