Every time
<SDLErrorDetails time="7/23/2020 3:41:04 PM">
<ErrorMessage>Object reference not set to an instance of an object.</ErrorMessage>
<Exception>
<Type>System.NullReferenceException, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</Type>
<HelpLink />
<Source>SdlTts</Source>
<HResult>-2147467261</HResult>
<StackTrace><![CDATA[ at SdlTts.ViewModel.TtsViewModel.<SetActiveDocument>d__112.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.CompilerServices.AsyncMethodBuilderCore.<>c.<ThrowAsync>b__6_0(Object state)]]></StackTrace>
</Exception>
<Environment>
<ProductName>SDL Trados Studio</ProductName>
<ProductVersion>15.0.0.0</ProductVersion>
<EntryAssemblyFileVersion>15.2.6.2831</EntryAssemblyFileVersion>
<OperatingSystem>Microsoft Windows 10 Pro</OperatingSystem>
<ServicePack>NULL</ServicePack>
<OperatingSystemLanguage>1033</OperatingSystemLanguage>
<CodePage>1256</CodePage>
<LoggedOnUser>ADMINSAM\Ahmed</LoggedOnUser>
<DotNetFrameWork>4.0.30319.42000</DotNetFrameWork>
<ComputerName>ADMINSAM</ComputerName>
<ConnectedToNetwork>True</ConnectedToNetwork>
<PhysicalMemory>50276084 MB</PhysicalMemory>
</Environment>
</SDLErrorDetails>
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