Protection code is checking integrity of protected application during decryption process. This message is displayed in case application is not properly decrypted.

There are few possible reasons for this:

1. Program has been externally patched (changed), damaged or infected by virus.

2. Remote protection: decryption key is not valid (most common reason).

- Be sure to use same Program ID for applications with same Application signature.

- Be sure to use correct project settings for calculation of activation codes.

If there are two applications with same application signature and different Program ID installed on same computer one of them will be wrongly decrypted and will display "File damaged!" warning message. Both application are sharing the same license data including Program ID (encryption/decryption key) and this is why one of them will be wrongly decrypted.

If "Reset license if crc errors are detected" option was enabled, protected application will display "File damaged!" error message and reset current license so that new site/mid codes are generated on next run. At this point you can generate new, valid activation code and pass it to your client.

In case this option was not enabled, there are two ways for getting out of this situation:

A) License removal feature is enabled:

Instruct end user to remove license and provide new site/mid code which are generated after license removal. Use the latest project settings to generate new activation code.

B) License removal feature is not enabled:

- Enable "Reset license if crc errors are detected" option and protect application again. This new release will reset license on remote computer and generate new site/mid code so you can generate valid activation code.

3. Program is changed during loading process.

This is done by OS and can not be avoided. You should turn off some encryption (code/data) options until this message goes away.