question

Hi @DanBrown-2027

Do you mean you deployed your Exchange 2013 on Windows server 2019? If so, that's not supported. Please correct me if I have any misunderstanding about your description.

In addition, when does this issue occur? What changes have been made in your environment recently which may lead to this issue(such as installing the security update and so on...)?

Have you checked whether users can log into OWA correctly? You could then check the application logs recorded in event viewer to see if any error.

Please also note that your CU12 is a quite old version, it's better to upgrade to the latest two versions(CU23 or CU22) for better support.

Below are some related links about the issue for your reference:
Can't sign in to Outlook on the web or EAC if Exchange Server OAuth certificate is expired
EXCHANGE 2013 ECP FAILS WITH 500 UNEXPECTED ERROR AFTER RUNNING HYBRID CONFIGURATION WIZARD WITH OFFICE 365
Please Note: Since the web site is not hosted by Microsoft, the link may change without notice. Microsoft does not guarantee the accuracy of this information.

---

If an Answer is helpful, please click "Accept Answer" and upvote it.

Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.

 (Get-AuthConfig).CurrentCertificateThumbprint | Get-ExchangeCertificate | Format-List

Method 1: Step by Step Solution for HTTP 500 Error

Step 1: Go to Search bar and type "Exchange Managmenent Shell".

Step 2: A new window will appear named as: Administrator: Exchange Managmenent Shell.

Step 3: It will start connecting to your local EAC ip.

Step 4: After connecting, type Remove-OwaVirtualDirectory ‘win2\owa

Step 5: Message will appear “Are you sure you want to perform this action? Outlook Web App virtual directory “win2\owa ” is being removed.

Step 6: Type y.

Step 7: Type New-OwaVirtualDirectory – Website Name ‘Default Web site’.

Step 8: Restart your Computer.

Step 9: Now re-login. Exchange Server http 500 Error will be fixed.

Method 2: How to Fix 500 internal server error in Microsoft Exchange

1. Create a separate virtual directory which doesn’t require SSL or any other authentication method to establish a connection with the server. In this way you could temporarily connect with the server but that might serve as a potential threat due to lack of authentication.

2. Alternatively you can enable the settings on the root Exchange directory for the front end server using Microsoft utility “Metaedit.exe”.
   Metaedit.exe

3. To determine the Maximum token size allotted to the user, use Microsoft provided tool : Tokensz.exe : By default the maximum token size- 8,000 bytes were allotted for the legacy versions; but for the later versions , token size was increased upto 12,000 bytes.

4. Insufficient permissions problem might be raised due to broken Access Control List inheritance in the Active Directory. To resolve this follow these steps:

   Launch Active Directory Users and Computers.
   Locate View >> Advanced Features.
   Select the mailbox and right click to explore the properties.
   Navigate to Security >> Advanced.
   Ensure that “Include inheritable permissions from this object's parent" is selected.

Active Directory Service Information

1. Alternatively you can re-add the existing users and new users to the Exchange. For that you need to access Active Directory Service Information:

   Open adsi edit.
   Locate the user in your existing domain.
   Expand the user details and remove the object “CN=ExchangeActiveSyncDevices”.

Tools that could be beneficial: http://test exchange connectivity.com helps to test the connectivity between the exchange server and the device.

Exchange Remote Content Analyzer: Helps to determine the connectivity issues between the exchange server and the deployments easily.