BizTalk Server 2020 TMS: String was not recognized as a valid DateTime

Last week a colleague of mine, configuring the BizTalk TMS service, reported me the error “String was not recognized as a valid DateTime”.

Starting the service, we found the following two messages in the Windows Server event log:

Figure 1 – String was not recognized as a valid DateTime

Figure 2 – The given key was not present in the dictionary

We tried to uninstall the service, reinstall it and reapply the BizTalk Server 2020 CU3 but nothing. Until then, we tried to change the regional settings and everything started working.

It’s not about the fact that they didn’t like a specific regional setting because putting the original one back kept working. Rather it appears that there was a condition that caused the exception and changing the settings resolved.

I wanted to share this little experience because we have not found anything about it.